Celica is the youngest daughter of the researcher Shuichiro Ayatsuki and his wife, who is only known as “Mother”. Tragically, “Mother” was greatly weakened by Celica's birth and died two years later in front of her eldest daughter, Celica's older sister Konoe A. Mercury. A rift grew between Konoe and Shuichiro as the latter was unable to deal with his grief and committed himself almost solely to his research. Celica was born with a unique ability to nullify seithr around her.
In the large part of their father's absence, Celica was raised by her older sister. She was strictly forbidden from going outside due to Konoe's fear of her being kidnapped. Still, Celica would sneak out to go shopping for food even at a young age. She would consistently ask her sister for training in magic, which was often refused by Konoe. 
One day when Konoe had gone on errands around Ishana, Celica ventured into the workshop of their home. When she opened the door, she was transported to the lowest level of the Phantom Field. There, she witnessed the memories of her father, discovering that he was not the monster that her sister through he was. Nobody found her and the two hatched a plan after finding out that Konoe had arrived on the highest floor. By making her witness the memories of Es, Konoe would not doubt the authenticity of her father's memories on the lowest floor. Nobody assured Celica that she would find Konoe, who had recently arrived on the highest floor of the Field.
Nobody eventually found Celica again, with Konoe in tow after she had witnessed the memories. As they were reunited, Celica could not help but notice that Konoe's general demeanor towards her had changed, becoming warmer and less like a guardian. The trio of girls made their way to the exit, where Nobody revealed that she would not be joining them in Ishana. Celica's pleas were silenced with Nobody's final riddles: “Who am I?”. As the riddle was delivered, the sisters were pushed through the exit and back into Ishana.
Now within their father's workshop, the sisters realized that they would be unable to return to the Phantom Field as the machine that brought them there had broken under the stress of bringing them back. A week passed, and Celica noticed that Konoe was constantly muttering Nobody's name to herself. She began to plead with her older sister to save Nobody, only to be told that Konoe had spent the last week fixing the machine that could bring them back. Soon after Konoe had returned from helping Nobody, the two sisters went to see their father for the first time in years.
Celica grew up and enrolled into the Mage's Guild on Ishana, becoming a student with average grades. In 2100, the Black Beast arose from Japan and the Dark War begun. Shuichiro was blamed for its appearance and he disappeared, presumed dead. Celica and Konoe grew much closer, but her sister's relationship with their father did not mend, leading to the sister bickering over the subject countless times. She became good friends with Trinity Glassfille, Konoe's best friend.
Konoe was chosen to become one of the Ten Sages - Nine. After the Canonization Ceremony, Celica and Trinity found the newly appointed Nine exiting the Ishanan Cathedral. Although Celica was disheartened that her sister had now changed her name, she was pulled into a giant embrace by Nine and told that no matter what, they would always be sisters, and that they would always love each other. Celica decided that they could celebrate by getting lunch together at the cafeteria.
At the cafe, the girls met Kazuma Kval, and Celica took an immediate shining to him, begging him to allow the group to sit with him. He allowed it, and Celica's happiness shone through the cold remarks that Nine was constantly dropping to the boy. As she ate spaghetti bolognese, Celica listened to Kazuma talk about classes. Before she could finish her food, Nine dragged her away and told her to stay away from him; Celica retorted and they bickered until a nearby television burst to life and ran the news that a Japanese survivor has been found. The sister's stopped in their tracks, but Kazuma fell ill - Celica attempted to help him, but her hand was smacked away and the boy ran to the infirmary.
Nine soon felt an unusual presence in downtown Ishana, so the trio of girls went to investigate. They found Kazuma in an alleyway next to a destroyed cobble road. She saw the boy was injured and offered to use her healing sorcery to recover his wounds but was rejected. Instead, the girls walked him back to his dormitory.
Together with Trinity, Kazuma, and Nine, Celica enjoyed a caramel cake and lemon tea in a cafe. She told the boy about her sister's incredible sweet tooth, telling him that her sickly sweet coffee is something she needs to relax her mind. She was then interrogated by her sister over her failing grades in lightning sorcery, but boasted of her ability to levitate for long distances. When Kazuma brought up Shuichiro, Celica and Nine began to have another one of their fights over the man, and both knocked tea over Trinity, causing her to greatly scold the two of them for their behaviour. Kazuma then ran away.
Celica was called out by Kazuma to the edge of Ishana. He dripped poison into her ear about Shuichiro possibly surviving in Japan, using the other survivor had been found recently as part of the persuasion. She learned that the survivor did not think he had been stuck within Japan for six years, but rather two because of a time distortion near a cauldron. Although hesitant, Celica learned that civilians could visit Japan, and it was not just a militarized zone. Excited, Celica also learned that there was a small hole in Ishana's barrier that she could escape through.
The young mage ran home and quickly wrote a letter addressed to Nine, Trinity, and Kazuma that told them that she would be going to find Shuichiro, but would return. She then excited through the barrier and used levitation sorcery to take her to a port that could ship to Japan. When she arrived, she stayed at a local hotel before making her way to the harbor. As she climbed a mountain to get to the port, Celica got lost, but she found a young man with a bright red jacket slumped against a tree. She immediately began to tend to him.
Celica took the man into a nearby shack and tended further to him. When the man finally awoke, he introduced himself as Ragna the Bloodedge, and Celica explained about her sorcery. She learned that he was suffering from amnesia and could not open his right eye. Together, they set off towards the nearby port town, with Ragna accompanying on the chance that clues towards his memories might be there. En route, they were ambushed by seithr-mutated dogs after Celica had left them lost with her terrible directions. Ragna defeated them, but Celica healed the dogs back to health, having felt sorry for them.
Almost immediately after picking up her map, Celica and Ragna were interrupted by a beastkin. The creature, who introduced himself as Mitsuyoshi, fought against Ragna, and the two battled until Celica stood between them, demanding them to stop. Mitsuyoshi told them of his objective - to head to Japan and capture Shuichiro. Shocked, Celica told him that Shuichiro is her father, and begged to know why her father was being hunted. She learned that he was likely responsible for the appearance of the Black Beast, and convinced Mitsuyoshi and Ragna to accompany her to Japan so she could find Shuichiro. Together, they made their way to the port town.
After securing an inn with Ragna and Mitsuyoshi, the three of them had dinner together. The beastkin soon left to gather intelligence, and the young mage went out to the harbor to gaze at the sea and stars. Ragna soon joined her, and Celica explained her family to him, talking about Nine's status as one of the Ten Sages and Shuichiro's numerous scientific awards. Lamenting on how she left Nine back on Ishana, Celica straightened her back and the two of them began walking back to the inn. She briefly lost track of Ragna, but still managed to find her way back.
The following morning, the trio travelled to Japan, catching a boat from the harbor to the country. Mitsuyoshi acquired transport from the United Nations, leaving Celica stunned and in awe of his position in the world. Ragna, Celica, and Mitsuyoshi sat in the back of a pickup truck as they were ferried around the barren wastelands that had once been Japan. Celica in particular was hopeful that in close to 100 years that the land might be fertile again, earning a chuckle from Mitsuyoshi as he lamented over the state of his country. Eventually, they found the Seioudai Sampling Laboratory where Shuichiro once worked and that Celica recognized from a visit in her childhood. Together, the trio entered the building, searching for the man but finding nothing. Once in the courtyard, they were attacked by a Remnant of the Black Beast, and Celica was helpless as she watched both Ragna and Mitsuyoshi give all their might to combat against it - they lost. The Remnant faded away, although Mitsuyoshi lost his eye from the encounter; Celic desperately tried to heal him, but the wounds could not be healed with her sorcery. They were met by a young vampire, Rachel Alucard, who offered them the chance to save him. Celica and Ragna took up the offer, and the former was shocked as the runes of teleportation sorcery flashed underneath them.
Inside the Alucard Castle, Celica and Ragna were ordered to stay in the parlor by Rachel as a butler carried the bloodied Mitsuyoshi into the inner sanctum of the Castle. Soon enough, both of them were introduced to the master of the Castle - Clavis Alucard, and his butler, Valkenhayn R. Hellsing. Clavis told Celica that he was the one who ordered the capture of Shuichiro, and she listened to his explanation on the discovery of the Susano'o Unit, the cauldrons, and Shuichiro's pursuit of the creation of a Kusanagi. Left to process the revelations set before her, Celica and Ragna were guided to the second floor by Valkenhayn as they were offered a place to stay for the night.
Later that evening, Celica found Ragna in the Castle's hallways. He expressed his worry about her after hearing about what Shuichiro had done; regardless, Celica told him of her resolve to still find her father, and the two agreed to continue on their search for the scientist. Clavis gave them a map for the First District and they ventured out to Japan one more. Now in the Kantō region, Ragna and Celica ended lost on a ragged trail thanks to Celica's direction. Ragna attempted to snatch the map away from her, but was interrupted by powerful sorcery attacking him. Turning to see the person who shot the sorcery, Celica turned pale as she saw it was Nine, with Trinity close behind.
Celica quickly jumped in front of Ragna to prevent Nine from hurting him. Both Nine and Celica entered into an argument about the man, with her older sister jumping on the offensive and immediately kicking Ragna when he interrupted their conflict. Celica began crying, and the situation was only diffused when Trinity offered them all tea. Nine and Celica, however, continued to argue, although this time it was about Shuichiro and the latter's search for him. The argument ended as Celica's resolve to search for her father swayed both Nine and Trinity into joining the search, and the new group travelled towards the First District.
Upon making it to the District, Celica was amazed by the technology used there. They soon discovered an elevator, and Trinity noted how the area was protected by alchemy. As they descended down into the depths of the area, the elevator suddenly began to rumble and violently stopped. Ragna created an exit, and quickly pulled Celica up to a safe footing alongside Trinity and Nine. He was unable to gain any good footing, and fell as Celica screamed out his name and helplessly stretched out her arm. The three girls made their way to where Ragna fell, and saw Hakumen. He barely spoke to the women before leaving. Celica quickly ran to Ragna's side, healing him of his injuries; reunited, the group continued to search in the facility before coming across a cauldron and an entrance to an unexplored room.
Gaining access through Ragna's brute strength and Nine's electricity, the group entered the laboratory. Hung high above them was the Kushinada's Lynchpin. Nine quickly read through the nearby research notes, becoming noticeably agitated as she did so, telling Celica it was all in Shuichiro's handwriting. Nine threw the papers onto the ground and began stomping on them, and Celica tried her best to save the documents from her sister's wrath. Upon inquiring on her sister's outrage, Celica was told that the device could defeat the Black Beast.
Moments later, Shuichiro himself appeared, gaunt from his captivity in the First District. Celica ran towards him, tears in her eyes, but their reunion was cut short as Nine commanded her to get away from him. She revealed that all of his research papers were not just on the Lynchpin but on how to merge Celica with it, and that her soul was ultimately the catalyst required for its activation. Nine pushed her father against the wall with a powerful shockwave, and Celica rushed to his side, seeing sanity slip from her father's mind as began to die, all while crazily exclaiming his achievement of having surpassed Relius Clover. When he finally died, Ragna held Celica as she uncontrollably sobbed into his jacket.
Mitsuyoshi appeared from the shadows, having listened to the conversation that transpired. He began to argue with Nine over what to do, being in favor of Celica sacrificing herself if it meant saving the world. Celica helplessly watched as the two battled over her fate, but had enough and ran between their battle. Both Ragna and Trinity helped to end the conflict diffuse, and the group attempted to reconcile and talk rationally through the situation.
Trinity prepared tea for the group, and Celica sullenly drank it, still reeling from the death of her father and the revelation that she could end the war. She told the group that she was willing to die if it meant saving the world, and expressed her heartfelt love for everyone she had met. Ragna interrupted her, and told them all that there was another way - if he charged into the Black Beast. Celica, nor the others, understood what he meant, but he revealed to her that he had a younger brother and sister, and that he did not want Nine to experience losing a sibling. Ragna playfully ruffled her hair before Nine and Ragna went to talk in private.
The ground began to rumble and the Black Beast itself had appeared. Celica stayed with Nine and Trinity as her sister cast a circle to teleport them out of the area. Ragna gave her his jacket and promised to come back for her after his encounter with the Beast. Mitsuyoshi also stayed behind to help Ragna in his effort, and Celica waved at them both before being teleported away, desperately clinging to the jacket he had given her.
Now again in the Alucard Castle, Celica learned that Clavis had passed away while they were in Japan, and that Rachel had become the new head. Mitsuyoshi finally returned some time later with Ragna's sword; Celica healed him as he gave her the sword and apologised, stating that Ragna had been swalllowed whole by the Beast. She wiped his crying eyes and embraced Aramasa, the sword of the man who sacrificed himself in her stead.
As the months passed after Ragna's disappearance, Celica returned to Ishana and continued her studies. Nine had assembled a team of warriors to combat the Black Beast, including herself, Hakumen, Mitsuyoshi (who had changed his name to Jubei), Trinity, Valkenhayn, and a man called Yuuki Terumi, who bore a remarkable resemblance to Kazuma. All that Celica knew of Kazuma was that he had disappeared from Ishana, seemingly unaware that Terumi and Kazuma were two souls sharing the same body. The group of warriors that included Nine would be known to history as the Six Heroes. In her free time, Celica polished Aramasa and fixed Ragna's jacket to the point of complete restoration.
In August, 2107AD, Celica daydreamed in the courtyard of the Mage's Guild. She dreamed of being in a pure white space, in front of her a singular mirror; she shook herself awake from the vision and saw silver hair in the distance. She called out "Ragna" to the figure, but when the figure turned around, it was Hakumen atop one of Ishana's hills. The two briefly talked, and Celica remarked that Hakumen and Ragna had a similar presence. Hakumen asked her if she meant Ragna the Bloodedge, but Celica was unfamiliar with his title, only knowing Ragna's given name. Abruptly, Hakumen left to find Nine, and Celica cheerfully jogged after him, attempting to follow his large strides.
Hakumen and Celica were found by Nine and the other Heroes, who immediately embraced her younger sister. She explained that she was with Hakumen and tried to persuade Nine that it was her fault for his absence. The atmosphere was soured by Terumi's arrival and he attempted to start an argument with Hakumen - Celica broke the confrontation and attempted to grab Terumi's arm, but he did his best to avoid her, something that Celica had noticed some time ago. The group disbanded when Seven and Eight reprimanded Nine for bringing them inside the Mage's Guild. Celica was about to leave with the others, but Seven grabbed her arm and demanded that she stay. Eight began to insult Nine's companions for not being human, and Celica stood up for them, telling Eight that they were risking their lives for the world and that they should be treated with respect. Both Seven and a stunned Eight then asked Celica if she would cooperate with their research, but Nine answered before Celica could register the question - no. Nine dragged her younger sister away from the two Sages and Celica begged her sister for information on what they had been talking about; Nine dismissed this by telling Celica that they were trying to use a failed weapon.
The sisters entered their favorite cafe, seeing Jubei and Trinity waiting for them. Celica greeted them both, but her hopes of having tea with all the Heroes together was crushed. She giggled and watched as Nine flirted with Jubei, causing the beastkin to become flushed and embarrassed. This interaction made Celica happy for her sister as she noticed that this was the first time Nine had allowed herself to become close to anyone who wasn't Trinity. The atmosphere was once again soured by Terumi's arrival; once he left for the other side of the cafe, Celica attempted to lighten the mood, but accidentally pulled at Jubei's tails - he flipped the table, sending Nine's thick coffee all over Trinity and her glasses. The sisters immediately began apologizing, knowing that they had incurred the young woman's wrath.
When the group left the cafe after Trinity's long rant, Celica and Nine bid the others goodbye. The sisters walked together back to their home, and Nine promised that she had a surprise of sorts for her younger sister, and that she would have to follow her into her workshop, a location that Celica hadn't visited since she was a child. There, Nine introduced Celica to a tall doll that would become her bodyguard while Nine was away on business concerning the Black Beast. Nine chanted a spell that bound the doll to Celica, and introduced her creation as the Deus Machina: Nirvana. Celica took Nirvana's hand and vowed that they would get along before the new formed duo went to prepare dinner. Celica was made aware by Nine that the research that Seven and Eight wanted Celica to be a part of would likely result in her death.
Celica attended her classes the following day. Nirvana was forced to stay in an office until her mistress' classes were over. As they walked back home, Celica was approached by Seven and Eight. Although she was without Nine, Celica stood up for herself, telling them both that she would not participate, a statement which was backed up by Nirvana taking a firm stance between the two parties. Both mage and doll left the Sages behind, with Celica deciding that they go to the local bakery to buy breads for dinner.
Nine insisted that Celica join a war council with the Six Heroes since she was worried about Seven and Eight's plans. Within the meeting, Celica was bored, not understanding most of what was being said and feeling as if she did not belong with such a group of amazing people. She leaned on Nirvana's arm and the doll attempted to pat its mistress on the head, reminding Celica of Ragna. The meeting was interrupted by Rachel as she teleported into the room, shocking Celica so much that she tipped out of her seat. She noticed a look in the vampire's eyes when she said that she could not intervene in the world - it reminded Celica of Rachel's father, Clavis. Rachel told the group that the Beast would appear wherever Celica was because Ragna's soul was sleeping within it. That night, Celica returned home and clung desperately to the Aramasa and Ragna's jacket. She told Nirvana that she would become bait for the Beast, and that she would attempt to convince Nine the following day. That night, Celica dreamed again of a white room with a singular mirror.
It took Celica some time to convince Nine that she should be bait for the Beast, but her older sister finally relented so long as both Nirvana and Hakumen were there to protect her. She, alongside the other Heroes and battalions of newly trained Ars Magus wielders, were deployed to a desert in Eastern Europe. Standing beside Hakumen and Nirvana, the knight asked her if she felt scared, something that she confessed while trembling. He attempted to comfort her, reminding her again of Ragna. Hakumen was curious, and asked if they shared any kind of resemblance, catching Celica off guard. She told him that they were both blunt, have a similar attitude, get into arguments with Nine, and that their history is completely unknown to her. The knight told her that she reminded him of someone he once knew; he then vowed to protect Celica at all costs. Happy, she bounded to his side, but their moment together was cut short as the Beast appeared in front of them.
Celica screamed out Ragna's name to the Beast after locking eyes with it. Hakumen jumped to protect the girl and engaged the Beast in battle. Celica was helpless and watched as the battle unfolded between the Beast and humanity; Nirvana attempted to pull her away, but she refused to leave her position. Several lights started glowing underneath Celica's feet as Seven and Eight appeared beside her. Nirvana covered Celica with her arms, but the girl's power was being drained out of her by the circle which summoned Gigant: Take-Mikazuchi. She was knocked unconscious, but the summoned weapon managed to repel the Black Beast for the first time in the entire Dark War. Nine ran to her sister and cradled her.
Celica was teleported to Ishana by Nine to receive medical attention. As she laid unconscious in a hospital bed, she dreamt about a completely white room, in which only a mirror was present. She peered into the mirror, seeing her body in its entirety and questioning whether this was her true self. As she began to stretch her fingertips toward her reflection, Celica awoke. Nine was laying by her bedside, asleep from the long hours spent patiently waiting for Celica to return to consciousness. As Celica glanced across the rest of the room, she saw Nirvana patiently waiting in the corner; moments later, Trinity entered the room and answered all of Celica's questions about what had happened on the battlefield five days earlier.
Nine was jolted awake by their conversation. The two sisters hugged and Celica began to unsuccessfully probe Nine for more information on what had happened. Nine refused, telling her to not worry. A doctor came to examine Celica and told her that while she had recovered quicker than was expected, she would still need to spend some time gathering her strength. Both Nine and Trinity left, leaving Celica to gather strength as Nirvana silently watched.
Celica fell asleep, but when she woke up a few hours later as the day turned to dusk, three Orbis Librarius Norma soldiers broke into her hospital room to arrest her. Confused, as she had never heard of them, Celica began to show fear – in that same instance, Nirvana scooped up her wielder and broke through the third floor window, cradling Celica in her arms as they descended to the ground below. More soldiers surrounded them, this time with firearms. They demanded Celica's surrender, but Nirvana went on the offensive until Celica ordered it to stop. The soldiers, even though they were spared, opened fire on the teenage girl; Nirvana blocked every shot with her body and bought time for her mistress to run from the scene. As Celica began to run, she fell and tripped. A soldier planted the muzzle of his gun against her head, using Celica as leverage to prevent the potentially fatal consequences of Nirvana's assault.
In a flash, the man holding the gun to Celica's head collapsed on the spot. Hakumen had arrived and dispatched him – he fought off the remaining soldiers, the Susano'o Unit being impervious to firearms, and picked up Celica over his shoulder. Hakumen defeated the soldiers with a single swing of his nodachi, which caused a shockwave so strong that it uprooted the nearby trees. After witnessing this sight, Celica instinctively ran towards one of the injured soldiers and began to heal him, but the strain caused her to fall back into Hakumen's arms. She fell unconscious as he carried her.
When Celica awoke, she was in Trinity's workshop, a location that is normally hidden from prying eyes. Besides her were Trinity, Hakumen, Nirvana, Terumi, Valkenhayn, and Jubei. Trinity explained what had happened earlier in the day and how the OLN was hunting them down. Before the group could decide what to do next, the sounds of a large explosion rung throughout the city. They left the workshop and ran towards the source, finding Nine locked in an intense battle against Seven and Eight. She couldn't believe her eyes and begged her sister to stop, warning her that more Sages were coming. Knowing that they would be outnumbered, the group retreated from the pursuing Sages and OLN. They ran through the busy Ishanan streets until two shadowy figures jumped in front of them. Jubei knew these figures and assured the group that they could be trusted. These figures guided them to a secluded forest where Nine was able to gather up her magical energy. Renewed, she then teleported the group far away from Ishana and into another location.
In this new location, Hakumen finally let Celica down. She was introduced to the two shadows, Suzukaka and Totokaka of the Kaka Clan, by Jubei, who also introduced them as his daughters. Celica had fallen in love with their cat-like features and became especially close to Totokaka as the two bonded with their mutual cheeriness. Celica listened as Jubei explained that the Kaka were his clones until they finally arrived at the Kaka Village. In the evening, Celica enjoyed the Kaka hot springs with Suzu, Toto, Nine, and Trinity. She found herself getting jealous over her sister and Trinity's body types, but enjoyed her evening, nonetheless. Remembering her doctor's earlier advice about getting rest, Celica went to bed early.
That evening, Celica had the same dream she had in hospital. The mirror was in front of her, but as she touched it, the dream ended and Celica woke up. She decided to go for an evening stroll, finding Hakumen perched atop a boulder, gazing at the crescent moon. The two talked about Ragna, and Celica listened to his theory that there were currently two versions of Ragna: the one that Celica knew, and one within the Black Beast. She asked if she could see Hakumen without his mask, but he refused. Celica then retired for the night, finding sleep at last.
The following day, Celica had a stroke of intuition. She asked Hakumen if he would follow her, and he agreed. Despite her natural ability to get lost, Celica's intuition guided her to an old train station. The heroes, including Suzukaka and Totokaka, followed the duo as they went down deeper into a old tunnel. Within this tunnel was a cavern, aglow with blue crystals. Suddenly, Celica began to glow herself. Hakumen then realized that the crystals were radiating Order, and that they possessed the same power to neutralize seithr as Celica.
A Kaka rushed into the cavern and asked that the group return to the village for urgent news. There, they learned that the OLN and Ten Sages were gathering up tens of thousands of people within a village in Asia. Nine quickly deduced that they were going to use these villagers in order to summon Take-Mikazuchi and fight the Black Beast. Celica begged her sister to come with them, as she wanted to meet Ragna once again. Eventually, Nine gave in, and the group formed a plan to stop the plot. 
Nine teleported the heroes, Celica, Suzu, and a group of Kaka near the Asian village. Rachel was there, commenting on how late they were. Nine ordered that Celica followed Hakumen and that she never leaves Nirvana's side. Nine, Celica, Hakumen, Jubei, and the Kakas went towards the village. Celica could not stop herself from helping the people who had collapsed. She then began to feel sick, realizing that it was the same experience that she felt five days prior when she was locked in the magic circle. Overhead, she saw the Take-Mikazuchi towering over the area. It battled the Black Beast, which had just appeared, and in their struggle, were forced down the summoning circle created by Seven and Eight. As the two giants collapsed into it, the circle exploded into a cloud of seithr.
Celica found herself in complete darkness. Ragna was there, reaching out to her, and the darkness turned into a forest similar to the one where they first met. He asked her “when” she is, but she did not understand. Various nightmarish wolves began to endlessly attack them until Nirvana finally cut through from the other side. Ragna insisted that Celica go with it, telling her it was a fight he had alone, and promised her that he'll see her again. She looked back and saw someone she did not recognize – a silver haired girl known as Nu-13. Nu stared back at her and smiled.
When Celica awoke, she was on a green hill in Ishana under a starless but clear night sky. The heroes, Suzu, and Eight were there with her. Eight looked at the city and screamed; Celica looked over herself and understood – the Black Beast had infiltrated Ishana, and was chewing on Take-Mikazuchi's shoulder. It looked up at the group, smiled, and disappeared. 
After Take-Mikazuchi had crashed into Ishana, Celica and the other heroes were given a brief respite from the Guild. They were allowed to help the recovery efforts the following day, something which came naturally to Celica as she helped cleanse seithr from the air and used her healing sorcery on the citizens who were caught in the impact. The sheer amount of effort she put had clearly taken its toll on her. Valkenhayn found her near the island centre, telling her that she needed to rest. She ignored him and ran towards an injured woman, healing her of her wounds.
Having healed the people around her, and not having rested recently, Celica collapsed into Valkenhayn's arms. He delicately put her down and chided her for overdoing it before the two were interrupted by Jubei. His warm attitude helped put Celica at ease, although she was reminded of the many lives who had been lost. He told her to take a rest as well, but Celica ignored them both and she bounded towards Nine, who had recently come out of a meeting.
Nine told the group that she suspected that the Mage's Guild and Duodecim were going to merge with the OLN. In that moment, Seven interrupted her to voice his opposition to the claim. Behind him were Three, Four, and Eight. Celica was in shock, as it was unheard of for so many members of the Ten Sages to be present in one location at any point in time. When Three said that she would be joining the battlefield, Celica blurted out a rude comment about her age, earning a stern warning from Four, but the jovial laughter of Three. The older lady then looked closer at Celica, but Nine stopped her from gaining a closer look. Eventually, Nine and Eight sparred into another shouting match, prompting Celica and Nirvana to go home and rest.
Fortunately, Celica and Nine's house was relatively unscathed from Take-Mikazuchi's crash but the impact had caused everything inside to fall. Both Nirvana and Celica began to clean the mess, and the young girl found an old family photo of when she was with Nine and Shuichiro. She showed Nirvana and told her that they'd take a new photo together, as she considered Nirvana family now. Nine came through the door and asked that Celica and Nirvana follow her outside. They met with Trinity and went Take-Mikazuchi, who was laying in Ishana's center.
Nine explained that she was going to take out Take-Mikazuchi's core and that it was no longer being used in the Dark War. The Black Beast had learned how deadly it was and would prioritise killing it before anything all – on top of that, it required innocent souls to be controlled. Nine asked Celica to control Nirvana to hold the core as she divided in half and as Trinity sealed it. Celica then accompanied Nirvana to a special room where the core was to be stored. Once the core was placed, both Celica and Nirvana left to go shopping before retiring for the night. Celica returned Nirvana to Nine for a brief period and was told about a plan to stall the Black Beast so she could create new weapons, the Nox Nyctores.
One evening, a day before the teams sent to stall the Black Beast would be deployed, Celica found Hakumen alone, staring out at the sea. She discovered that he would be among those deployed and, fearing she might not have a chance in the future, told him about her chance encounter with Ragna back in the Asian village. She explained that she saw a girl, Nu-13, there as well. Celica saw his body language change and he asked her to return home. Initially hesitant, she agreed. 
Two months later, Celica watched as a ship returned to the Ishana pier carrying the remnants of the army sent to stall the Black Beast. All the soldiers were injured bar Hakumen. Celica ran to Jubei and began healing him, although he tried to tell her to heal others who were more seriously injured. She ignored him and healed his wounds before going to heal the other soldiers as wounds inflicted by the Beast struggle to heal, even with healing sorcery.
Nine summoned the heroes and Celica to her workroom within the Mage's Guild. There, Nine introduced the Nox Nyctores and handed them to their wielders: the Arma Reboare: Muchourin to Trinity, the Mucro Somnio: Musashi to Jubei, the Interfectum Malus: Ookami to Hakumen, the Geminus Anguium: Ouroboros to Terumi, and finally the Deus Machina: Nirvana back to Celica. Valkenhayn refused to have a weapon since he could injure the Beast by virtue of being outside of Logic. Nine made it clear to all of them that these weapons would have to be sealed after the war as their power would distort future history. Celica became teary eyed as she realized that she would lose Nirvana after the war despite becoming so close. Nine told her sister one more thing: if they were to fail, Celica would have to use Nirvana to summon Take-Mikazuchi and finish the Black Beast in one final blow. Celica accepted this responsibility, believing it would never come to that.
Ishana rallied together with the remainder of humanity to strike the Black Beast for one final time. Hakumen summoned the other heroes and Celica to Trinity's workshop. There he revealed that they were not going to be able to kill the Beast. Their mission was simply impossible unless they tried something else. To this end, Hakumen proposed that Celica go inside the Beast and meet with Ragna. Together, they could fight against the heart of the Beast, Nu-13, causing the Beast to lose some of its intelligence and succumb to its base desires of wanton massacre. It would be baited to follow after a large army, bringing it closer to the Kaka Village and the cave near it which was filled with crystals of Order. These crystals neutralize seithr, so the Beast will only get so close. Once it was close enough, the Ten Sages and strongest members of the Mage's Guild would work together to teleport the Beast above it. The Black Beast would be drastically weakened and could then be killed. In order to do so, however, both the body and the heart would have to be killed at the same time as they shared a life-link. Jubei offered up a solution to get Celica inside the Beast: using the Hihiirokane to cut through it, and then using Nirvana to retrieve her. Nine was vocal in her hatred for the plan, feeling powerless as she had to offer Celica in danger yet again. Celica ran to her sister's side and cupped her cheeks, noticing that Nine had lost a lot of weight from the sheer stress of the war. She told her sister that this was the only way forward, and eventually managed to persuade her to go through with it.
Ten days before the Beast was due to appear near Ishana, Celica was present in a meeting held by Nine where she explained Hakumen's plan to the various organizations within Ishana. Nine failed to mention Hihiirokane, the Beast's heart, or Celica's involvement. They would not understand these details and if they did not understand them then they would not support the plan. When the meeting concluded, Celica returned home with Nirvana and packed her things. She would be meeting with Hakumen and Jubei on the mainland to prepare for their encounter with the Beast. As she left her home, she met Nine. The two spent some time together as they walked toward the harbour. For one brief moment the time they spent seemed like the war wasn't happening and it was like old times. But this bliss was cut short as they reached the pier and Celica boarded the boat, saying goodbye to her sister for a trip that she might not return from.
Celica was nervous for the day ahead, but knew she had to do what she could. On December 31st, 2109, the Black Beast finally appeared with its sights set on Ishana. Hakumen and Jubei engaged the Black Beast, and the plan was going smoothly as Jubei cut open a large wound into the Beast's shoulder, allowing Nirvana to carry Celica into the Beast. As she fell into the darkness, Celica cried out for Jubei to not let the Beast defeat him. When inside the Beast, everything was pitch black. Celica screamed out Ragna's name countless times and, finally, the black scenery turned into a lifeless forest reminiscent of the one where Celica and Ragna had first met. Nirvana in tow, Celica ran forwards and finally found Ragna.
When they met, Ragna questioned why she was still in the Beast. Due to the distorted flow of time within the Beast, it was as if she had not left months earlier. Celica explained the situation and Hakumen's plan to him. Ragna recognized Hakumen's name, something that made Celica smile with glee as she was never able to get a straight answer out of Hakumen about their relationship. Ragna suddenly went on guard. Behind Celica stood Nu-13. At that moment, Celica realized that to stop the Black Beast would mean to kill the young girl in front of her. Nu, however, did not care. She told Ragna to kill Celica or she would do it herself. Nirvana braced Celica as Ragna and Nu began to fight within the mirage that was a lifeless forest within the Black Beast.
Ragna eventually won, killing Nu and the heart of the Black Beast. Celica and Ragna did not know what to do next. Ragna had to return back to his time and Celica had to escape the Beast. Rachel then appeared, but her mannerisms were different. She explained that the Beast was like a giant cauldron, and that she would take Ragna back to his own time. Ragna waved goodbye to Celica, telling her to tell Nine that he said ‘hi'. Nirvana scooped up Celica and Rachel used her Drive to propel them into the air. Celica and Nirvana were then teleported outside of the Beast by Rachel. They were taken next to the other heroes as the Beast's body deflated down into the shape of a man. Celica saw its shape was similar to Ragna. Hakumen walked forward and decapitated it with one swing of Ookami. The Dark War was over, and the Black Beast was dead. The only person mourning was Celica, who could not help but feel immense sorrow for the body, for the Ragna who had become the Beast. 
One month passed. Celica was back in Ishana. Due to her efforts in the war, she was given a graduation certificate and she decided to not return to school. Nine, Hakumen, Jubei, Valkenhayn, Trinity, and Terumi were now called the Six Heroes. Nirvana was beside her, yet to be sealed away as the paperwork for it had yet to be done. Suddenly Nirvana acted on her own, guiding Celica to the Ishana Cathedral. Despite Celica's protests, she followed until she ended up in the basement of the Cathedral. She took one step forward and the entire scenery turned pure white. A lone mirror was in front of her. Celica was then found by Trinity, who took them back upstairs. The reflection in the mirror, however, banged against it. She was left behind, but then she suddenly heard a voice in the background – a voice that sounded similar to Nine's. This Celica was turned into a Chrono Phantasma (Those Who Should Not Exist) by Kokonoe, the future daughter of Jubei and Nine. The real Celica forgot about this, as it all felt like a blurred dream.  Nirvana was sealed and buried some time later, in what would eventually become the 4th Hierarchical City of Naobi.
Celica became a nun, with her church being built by Nine and Jubei. It was erected over the sight of the Beast's death, and Celica greeted her sister and Jubei as they visited - they were soon to be wed. Celica offered them tea given to her by Trinity, and learned that they wanted to hold their wedding at her church. Overwhelmed with happiness, the three sat down to tea together to discuss the ceremony. Celica eventually wed both Jubei and Nine, and soon became an aunt to their newborn - Kokonoe. Tragedy struck, however, as Terumi killed both Nine and Trinity before being dragged into the Boundary by Hakumen, who sacrificed himself to do so. It is presumed Jubei broke the news to Celica.
A mage who lived during the Dark War, and the little sister of the Six Heroes' Great Mage "Nine." By nature, she excelled at restorative sorcery and innately had an unconscious ability to surpress seithr, so Kokonoe summoned her into the present era as a "Chrono Phantasma." Equipped with an Idea Engine created by that same Kokonoe, the automaton Minerva waits together with Celica for a reunion with Ragna, who challenges his new trial with resolve.
|Stage 1: Lambda-11|
Celica: Huh...this is weird... What's going on here?
Celica: Um...am I lost? He he, well, I guess I can't really be lost since I'm not actually going anywhere.
Celica: Well, my name's Celica A. Mercury. Who are you?
Celica: Minerva? That's a lovely name. It's nice to meet you!
Celica: Oh, somebody's here.
Celica: Hi, I don't think I've met you before either. I'm― Aaah! Th-That doesn't look very friendly...
Celica: Gone... What do you think that was?
Celica: You think so too? Although, that would mean...
Celica: Well, let's just keep moving! Follow me!
Celica: Oh, don't look so nervous. I'm completely sure this is the right direction!
|Stage 6: Carl Clover|
Celica: Wait...have we been here before?
Celica: Hrm. Now I'm really confused... What should we do? If this keeps up we really WILL be lost.
Celica: Huh? What's wrong? Nirvana...?
Celica: Hi, it's nice to meet you. I'm Celica A. Mercury. That's, um, that's Nirvana, right? Oh, I missed you so much, Nirvana! I have to say, this is a real surprise. I didn't think I'd see you here! You do remember me, right? Ha ha ha, oh jeez, this feels so weird. I saw you just a little while ago...
Celica: I'm glad you're not alone, though. You've got this boy now, I guess? That's good... Um... I'm guessing I have to fight you too, don't I?
Kokonoe: ...Ah, you've noticed.
Celica: Oh Kokonoe, you're such a kidder. You were watching me the whole time, weren't you? If you'd just said something I would've been happy to help out!
Kokonoe: I've had a long, hard think about it, and the only way I can get you and Minerva working― wait, how do you know her name?
Celica: Huh? Um, she told me.
Kokonoe: Y-You can understand her?! I haven't implemented a speech mod― nevermind. Look...
Kokonoe: From now on I want you to follow Minerva. Say it with me FOL-LOW. Don't rush in in front of her, just stick close and most importantly BEHIND. Now say it back to me.
Celica: Okay, okay, I get it! Message received! I just need to follow her, right? Easy enough. I guess we'll be seeing a lot of each other, Minerva!
Kokonoe: You remember your job too. Don't let Celica out of your sight.
Celica: C'mon, let's go!
Kokonoe: W-Wait! Didn't you hear anything I just said?!
|Stage 7: Relius Clover|
Celica: Whoa, she looks a whole lot like Nirvana. Hey...do you know who that man in the mask is?
Kokonoe: That's Relius Clover, but you're just seeing some fragmented data, ignore it. Now, about your next adjustment...
Celica: Relius Clover... Um, have we met before...?
Relius: Ah, so it was you after all, Kokonoe.
Relius: Excellent work. This is quite an impressive doll you've created.
Celica: Huh? He can talk?
Kokonoe: No...no, that's impossible! I built this world to be completely isolated... Relius, how in the hell did you get in here?!
Relius: "Get in"...? Ah, I see. Such comprehensive data, Kokonoe. But I would expect nothing less from you. Though perhaps it was...too comprehensive?
Relius: Your recreation of me was near enough to the real thing that I sensed a shadow of myself and materialized in its vicinity.
Kokonoe: What?! You son of a― Celica! We'll abort the whole thing! I'm gonna format the entire system! ...Why aren't you disappearing?!
Relius: Oh, don't worry, I'll be out of your hair just as soon as I get what I want.
Relius: I confess I'm curious about who's in there.
Kokonoe: No way in hell am I letting you figure that out! Celica! Minerva! Kick the shit out of this bastard!
Celica: O-Okay, I'll give it my best shot!
Celica: D-Did we win...?
Relius: Hm. The best I can expect from a copy, I suppose. Still. My thanks, Kokonoe. An existence even I cannot Observe. The Chrono Phantasma... Fascinating.
Celica: Chrono Phantasma...?
Kokonoe: Don't listen to him, Celica!
Celica: ...He's gone.
Kokonoe: Damn you, Relius... This wasn't part of the plan. No time to waste on final adjustments now...
|Stage 8: Kokonoe|
Celica: O-Oh, hello. You're in here too?
Kokonoe: Little change of plans. I'm going to adjust you myself.
Celica: Y-You what...?
Kokonoe: I can't let our little "problem" get the upper hand. This might sting a little, but unfortunately I don't have time to be gentle.
Celica: Wh-What? Problem?
Kokonoe: Ugh... Well I can't just leave his data in here, can I? Once we're finished with your adjustments I'm just going to wipe the whole damn thing.
Celica: What?! Then Nirvana and all the other people I've met are just going to disappear?!
Kokonoe: ...They're just data. They're not real. They're simulations I created.
Celica: Y-Yeah, but... then that means I'm not really here either, doesn't it?
Kokonoe: ...I don't have time for this. We're starting.
|reason for being|
Kokonoe: Hmm. Better than I thought. Would've been nice to spend a little more time with you, but...
Celica: Um, Kokonoe, do you really have to delete this world?
Kokonoe: Don't worry, you won't remember any of it. Just to be safe I have to delete everything. All I'm leaving is the calibration data for you and Minerva.
Celica: Oh...but, um...
Kokonoe: Look, I'm sorry to have to tell you this, but we don't really have the time to wallow in sentimentality. I've got another job I need you and Minerva for.
Celica: ...Yes, you're right. That's why I'm here, isn't it?
Celica: Well, don't worry, I'm sure I'll remember everything. Like talking to Nirvana, and meeting Minerva... Or even talking to you. All that stuff is important to me. So I think I'll probably remember.
Kokonoe: Uh-huh. Well, I'm about to hit the button. You ready?
Celica: ...See you.
Kokonoe: Boy, she sure is...something. Anyway, that's the last of the preparations. Heh... Things are about to get real busy.
Kokonoe: ...After what I've done, I'm not going to ask you to forgive me.You're our only hope, Celica. So please, look after her for me... ...Minerva.
She met Iron Tager and Kagura Mutsuki  In Yabiko, Celica was separated from Tager and she found Ragna laying on the ground heavily injured and patched him up with her sorcery, also meeting Taokaka. She realised that Ragna did not recognize her at all and he left her, telling Celica to not get involved with a guy like him. Tager then found her and they returned to the NOL Yabiko branch. 
She saw as Kagura defeated Ragna and threw him into a cell.  Even as Kagura teased the Grim Reaper, Celica stood up for Ragna, talking about how brave and considerate he is; Ragna was begging Kokonoe for death due to the sheer embarrassment. She stayed next to Ragna as he was in his cell, telling him that Kokonoe had ordered her to watch him. Rachel and Noel soon came to the basement and the vampire told them all the story of the The World. Celica intently listened to the sad story. Kokonoe entered the room and handed a switch to Celica, telling both her and Ragna that she had attached a Multi-Dimension Bomb to Ragna at the cellular level and that when the two of them were separated over a certain distance, it would detonate. They were forced to be together but they ended up lost on their way to meet Kagura and Hibiki in the former's office.
In the office, Kagura revealed that Celica was the key to activating Kushinada's Lynchpin. She witnessed as Jin Kisaragi entered the building but left on Kagura's orders when the brother's got too rowdy. She soon found them arguing again in the Yggdrasill Seed and put an end to their fight, healing them both, and trying to make them see eye-to-eye.
The following day, she was at the large meal prepared by Hibiki and helped feed Ragna since he was making a mess; Celica attempted to do this for Jin but was rejected, and instead told off Tao for the food over her face. Later that evening, she talked about Nine to Ragna, although he still did not know who she was, and the two shared a tender moment together as Ragan promised he would protect her from anything. That same evening, Celica healed Noel's wounds after she was attacked by Arakune.
The following day at the Battle of Ragna the Bloodedge, Celica took on the alias Ayatsuki and posed as Kagura's secretary, meeting Tsubaki Yayoi for the first time. She engaged in casual betting with Rachel over who would win in each round, always rooting for the underdog and always losing each bet. She watched Ragna save Bullet from Azrael]], taking the young woman to her sisde. Azrael launched a punch at Celica to stir Ragna, but Rachel threw Gii in that direction, blocking the attack. She later healed Kagura, Ragna, and Bullet, but noticed her healing power was dwindling when she missed a scratch on Ragna's neck; they were met by Rachel, who told them to meet her in Ibukido the following day. Celica wished Makoto, Jin, and Noel good luck with freeing Tsubaki. She was relieved to see they were successful
Later that day, Celica saw Terumi and Phantom in the Colosseum outskirts, recognizing Phantom and being escorted back to Kokonoe's lab by Tager. The toll of having absorbed so much seithr was too much for her. The following day, Ragna, Celica, and Noel met Rachel in Ibukido, and Celica knew that this was the point where Ragna would soon meet her for the first time, all the way back in the era of the Dark War. She wished him good luck, her memories of the place they met being used by Noel so that Ragna could arrive there safely. When Ragna returned, Celica was reunited with him properly and helped him sort through his twisted memories. She tried to keep up with him as he stormed away to Yabiko's NOL branch to find Kokonoe.
Celica watched the argument between Kokonoe and Ragna, but told the man that she regretted not having used Kushinada's Lynchpin back in the Dark War. The lives that were lost when the Black Beast began to move again caused her extreme grief; Ragna told her that if she sacrificed herself then Nine would have likely never found the strength to complete Ars Magus, and the conversation was moot. Rachel arrived shortly afterwards and revealed to them all that there was another way to activate the Lynchpin, with everyone deducing that it was possible through using the Phoenix: Rettenjo, which held the soul of the Tenjo Amanohokosaka. The group then decided to activate the Lynchpin as soon as possible.
At the 8th Hierarchical City of Wadatsumi, Celica, Ragna, and Noel were guided to the Wadatsumi Castle by Hibiki. Through Noel, they were able to discover the entrance to where the Lynchpin was kept, finding Bang Shishigami keeping guard over it. Celica watched as Ragna won Bang over and told them that if all else fails that she should still be sacrificed to make sure the Lynchpin was activated. The group was then met by Relius Clover, Ignis Clover, Litchi Faye-Ling, and Nu. 
Minerva came to protect Celica and Noel, and Celica was reintroduced to her companion. Minerva helped carry her when the heavy seithr in the air took its toll on her body. She, alongside Ragna and Noel, escaped from the castle basement thanks to Makoto and Tsubaki, arriving at the surface. Celica watched as Take-Mikazuchi fell to Earth and she agreed with Kokonoe on releasing her limiter, stopping the flow of seithr in the air and making the Nox significantly weaker. She also managed to convince Hakumen to help them, but she had only 10 minutes before her body would give out.
The battle was successful, and after Ragna opened a hole in Take-Mikazuchi, Celica, Ragna, and Minerva jumped inside. The landscape took on the cauldron in Ishana and Celica watched as Ragna defeated Nu. She lightly joked about it being a good thing she entered since Ragna had not thought of a way out, so Minerva helped them exit. On ground level, Celica watched as Ragna was sent berserk by Izanami interfering with his Azure Grimoire. On Jin and Noel's orders, Minerva grabbed her and tore into the other direction, leaving Celica helpless as Ragna not only mortally wounded Jin, but went missing.
Back in the Yabiko NOL branch, Celica gave her all to heal Jin, but she could only do so much. During this time, she grew closer with Tsubaki, but needed space to work her sorcery. Hibiki checked up on her every 3 hours to make sure she did not exhaust herself.
Kokonoe was ousted from Sector Seven by the Committee, and Celica was forced to be transported to the 6th Hierarchical City of Yabiko. She found the journey long and boring, but was allowed free reign later that afternoon. She requested to Kokonoe that she could visit somewhere – her own grave. Kokonoe accompanied her and gave her some time alone to think, but that was cut short by the arrival of both Izanami and Phantom. She ignored the Imperator and stared straight at Phantom, calling out for her sister, but the shadowy figure did not respond, teleporting them away.
Kokonoe ran back to Celica's side and the young mage told her niece about the appearance of the Imperator, and kept wondering about whether Phantom really was Nine or not. When they returned, Celica met Hibiki Kohaku, although he lectured both her and Kokonoe over their recent acts. As they left the room they were met by Makoto Nanaya, who was ordered by Kokonoe to guide Celica across Yabiko. The two became fast friends, boasting about their friends and family while also feeling relieved at being able to live a normal life for even a short time.
Celica was given a short tour around Ikaruga by Tager before being separated as they explored, her heart was filled with glee at the prospect of meeting Ragna again. Celica caught sight of Nirvana, and followed after her, meeting her new wielder, Carl Clover. The boy was cold and threatened to hurt her since she kept calling the doll Nirvana but was saved by Hakumen. After Carl retreated, Celica and Hakumen decided to stay together, both talking about finding the ones they loved, referencing their conversation in their first battle against the Black Beast. They were interrupted by Azrael, who battled against Hakumen with all his might. Celica created a bright light to ensure they could escape from the Mad Dog, and were soon found by Jubei, Valkenhayn, and Rachel. The group were teleported to the Alucard Castle and Celica was reunited with Trinity, and the girl forgave her for everything that happened since the Dark War. Celica did not contribute to the plan on killing Terumi, as Rachel teleported her back to Yabiko so she could meet Ragna.
Later, Celica returned to the Alucard Castle with Rachel and helped in the plan to kill Terumi. She went with Jubei and Hakumen after Trinity forced him to materialize in the real world, citing that she knew her presence would weaken him. She watched as he was defeated and then teleported away by Phantom, who stared at Celica. When Phantom disappeared, Celica confirmed to Jubei that Phantom is Nine, knowing it was true deep down in her heart. 
A mage who lived during the Dark War, and the little sister of the Six Heroes' Great Mage "Nine." By nature, she excelled at restorative sorcery and innately had an unconscious ability to surpress seithr, so Kokonoe summoned her into the present era as a "Chrono Phantasma." Awakening in the unfamiliar city of "Kagutsuchi," she wanders with Minerva at her side and searches for one important to her, Ragna.
Act 1: Phantom of Labyrinth
|Stage 3: Taokaka|
Homecoming -Orient Town-
Celica: Hmm... where is this? It's not Ikaruga... is it? Oh, where's KMiss Kokonoe...? Hey! I wonder what that is? Let's go check it out, Minerva!
Taokaka: Meooow... Tao's no good. Meow.
Celica: Huh? Taokaka? What's the matter? Are you alright!?
Taokaka: Ahh... Tao's too... hun...gry. Meow.
Celica: Hungry? Oh, well that's not too bad, then. I thought you were injured or something. Whew.
Taokaka: It's not good at all, meow! Tao's starving, meow. Buuuut, who are you, meow? That doesn't matter! You fight Tao, and if Tao wins, you have to buy me food, meow!
Celica: H-Huuuh!? W-Wait a second--!?
Celica: Umm, I can see that you're very hungry, but I don't have any money, either. Was it the NOL or something? Maybe if I take you to Mister Kagura, he can give you something to eat...? ...Hm, where's the NOL branch again?
Taokaka: En-Oh-Elle...? Oh, you mean the Library? Tao doesn't like those guys, so buh-bye, meow!
Celica: Huh? Oh, no, there she goes...
|Stage 6: Kagura Mutsuki|
Celica: Whew, I found you! Mister Kagura!
Kagura: Hm? Uhh, h-hey there... Long time no see?
Celica: Long time no see? I don't think it's been that long since we were separated?
Kagura: R-Really now? Haha... (Shit, I didn't do anything with this girl, right? She seems really... young.)
Celica: Everyone's acting really strange... Did you forget about me? Kagura?
Kagura: O-Of course I, uhh... remember you... I think! So, what do you want?
Celica: What's happening back there? It feels really bizarre... It's like something is calling me...
Kagura: Hey, wait a second! You can't go there, that's off limits to civilians!
Celica: ...I know this sensation. I've felt it before... Ragna...?
Kagura: HEY! I told you to stay away from there! You listening to me!? Gah... I hate using force, but you give me no choice.
Kagura: Ack, dammit! I can't fight a cutie like you!
Celica: I'm sorry, Mister Kagura. Let's go, Minerva! Ragna...!
Kagura: Whoa, there--!
|Stage 7: Ragna the Bloodedge|
Celica: Ragna! What's the matter, are you okay?
Ragna: Ugh... gah... Who the hell... are you?
Celica: Who am I? It's me, Celica! Are you in pain? Let me see it! I can heal your wounds, you know.
Ragna: Don't touch me!
Ragna: K-uh... don't you dare get close to me. Stay away!
Celica: There's so much seithr concentrating around you... Ragna, no! Don't lose yourself in it--!
Celica: Minerva? Let me go! Ragna is...!
Ragna: I can't hold it in...! G'gaaaaaaaaaaah!
Ragna: Guh... uh.
Celica: Hang tight. I'm going to fix you right up, okay?
Ragna: Stay... away.
Celica: ...! Watch out!
Celica: Ragna, no! Give me your hand! Ragna! Don't fall down! (What is this... flowing into me? From beyond the flickering flames... This is... information? No, memories... Ah--)
Celica: (Who is that? Is that you, Ragna? And you're with Jin and... someone who looks like Noel... ...Everyone's so happy. It's so warm, and nostalgic. Oh, I wanna go there, too...) Yes, I wish I could've stayed by your side... (Huh? What am I saying--?)
Nine: Celica! That's enough...
|Stage 8: Nine the Phantom|
Celica: Huh? Huh!? Where is this? Sister!? Oh, I see now... this is inside your barrier. Say, do you know what happened to Ragna?
Nine: Celica, the man you just encountered... is not real. This is a space in which the dreams of the chosen are turned into reality. The man you saw is an illusion created through your desires.
Celica: An illusion...? Oh, thank goodness. I was afraid the real Ragna fell down into that pit.
Nine: Yes... And that vision you saw, it's like a mirage created by the Boundary. Nevertheless, it is also a tired sight that has been repeated and warped over time...
Celica: Then was it something that actually...happened?
Nine: I don't want you to ever bear that loss again. That's why you cannot be here!
Celica: Sister, stop! I have no idea what you're trying to do! But there's something I want to do, too! There are people I want to save, and those I want to protect! ...I can't go to this other place you want me to. Not yet!
Nine: Stop irritating me! Why do you have to push yourself this far!? What else do "YOU" want to make her do!? Master Unit: Amaterasu!
Nine: ...But if the world that you want, Celica, can be created... Let me share with you the one way you can make it true.
Nine: Before the Day of Reckoning, the Imperator... No-- Izanami must be defeated. By your hands.
Act 2: Nightmare Memory
|Stage 3: Litchi Faye-Ling|
Celica: Hmm... Where am I? I thought I was in a different city a few moments ago, but when I realized it, I was walking around Ikaruga. Could this be Sister's doing? Say, Minerva. Let's ask that person right there! Excuse me~?
Litchi: ...!? You're...one of the chosen...
Celica: Chosen? Oh, are you talking about that thing about defeating Izanami and making your wish come true?
Litchi: If you alraedy know, that speeds things up. I will get rid of you right now... That is the iron rule among the chosen.
Celica: H-How could they be so... huge? You might even give Sister a run for her money...
Celica: ...Let's do this, Minerva. I don't care if you're a chosen or not. I've got my own reasons. I can't lose this fight!
Celica: This proves it, Minerva. Size isn't everything, right?
Litchi: *Sigh* I was serious... and yet you're making a joke of this.
Celica: You're Miss...Litchi, right? I'm sorry to interrupt you, but... I don't think this means all's lost. I'm sure there are still other things you can do to make your wish true, so...
Litchi: Hehe... It's alright. I won't break into tears from being the tragic heroine or anything. You should be going now.
Celica: ...Okay. See you around, Miss Litchi.
|Stage 6: Platinum the Trinity|
Celica: That's strange... I thought Kagura headed in this direction. Did I get my bearings wrong? Oh, Miss Platinum!
Luna: Hm!? Who're you?
Celica: Huh? It's me, Celica... Wait, I can't sense Miss Trinity from your staff...
Sena: Say, Luna... I think this person is one of the chosen, too.
Luna: That means if we beat her up, we're one step closer to Izanami!
Celica: Are you here to see Izanami as well? Did Miss Trinity tell you to do that?
Luna: Gah! Who the heck is this Trinity person supposed to be!? Although it does sound kinda familiar... Anyway! If you're one of the chosen, then there's only one thing for us to do. Get ready because Luna feels invincible right now!
Luna: This can't be... happening... Wha-!?
Celica: Hey, don't ignore me. You seem very unstable right now, Platinum...
Luna: We're not unstable! I'm feelin' like a rock sta... Ahh...
Sena: Luna... I think we need a break. My head feels all...dizzy...
Celica: You've done enough fighting for the day. Why don't you go rest over there, mmkay? (I probably shouldn't be here any longer... What would Sister do if she were here...?)
|Stage 7: Jin Kisaragi|
Jin: ...It's you. Looks like you've managed to evade the effects of the Embryo.
Celica: Thank goodness, you remember me, Jin. But...what happened to you!? You're injured!
Jin: Not a concern. Now, get out of my way. I'm in a hurry.
Celica: ...Are you going to Izanami? No, you can't! You're so badly hurt right now!
Jin: This has nothing to do with you... If you stand in my way, then I won't hold back...
Celica: That's my line! If you insist on going, then I'll have to stop you by force!
Celica: ...Oh! So, Miss Trinity healed your wounds, right Jin?
Trinity: I'm sorry I couldn't explain sooner... but I didn't want to interrupt and, I guess I missed my timing...
Celica: ...Yeah...but after hearing that, that's all the more reason I can't let you go. I'll confront Izanami.
Celica: Even if you weren't injured, your strength is limited right now, right? You should save it for when we really need you, Jin. I'll go see Izanami and get answers to our questions. So Jin, you need to take better care of yourself, okay?
Celica: Eeek!? An earthquake!?
Jin: No, above us!
|Stage 8: Izanami|
Sight of Gods
Celica: I've finally found you, Miss Izanami. Where's my sister? What were you two trying to do here?
Izanami: ...And you... What brings you here? You are but an apparition... Did you think you could fight me?
Celica: I came to stop you. You and Sister are trying to destroy this world. And that's probably going to make Ragna, Jin, Noel... and the people of Ikaruga really sad. I can't let you do that.
Izanami: You fool...the world has long been destroyed. I am just righting the wrongs within it. If you are standing here, then you are one of the chosen. Defeat me, and I shall bestow upon you the Azure. It shall open your eyes... ...to the truths of this world...and your own stupidity.
Celica: Let's go, Minerva!
Izanami: Brilliantly done. A promise is a promise... Here is the Azure. It contains all the information you can possibility want within. Even information about your sister... It's all in there.
Celica: (What is this flowing into my head... Information? History...? No, memories...?)
Celica: (This voice... the Black Beast. Ragna's...voice.)
Celica: (This is from when they fought the Black Beast...)
Nine: Give me a break!
Nine: This is the world's true form? Like hell it is! Then why the hell did we put our lives on the line!? We didn't spill all this blood... ...so the gods can have a little family dispute!
Celica: (Of course... Sister knew about it. All of it...)
Celica: This is a...church? The world is rebuilding itself...
Izanami: The world will repeat its stupidity. Your sister is simply trying to put an end to that tragedy.
Celica: That's not true! No matter what the world looks like... that doesn't give anyone the right to hurt the people within it! I want to protect the people I love, so...
Celica: I'm going to stop whatever it is you and Sister are tying to do!
Izanami: Your determination is a drop of water in the ocean. It doesn't matter how one resists. She will grow tired of an unchanging world... and bear our demise.
Act 3: The Replacement Blue
|Stage 3: Nu-13|
Nu-13: ...Target's combat ability, weakened... Terminating target...
Celica: Noel! Are you alright!?
Nu-13: Target identified... Celica A. Mercury. I don't like you... If you get in my way, I will kill you!
Celica: Noel, get away from here... I'll stop her.
Celica: Don't worry. I have Minerva on my side... Besides, you have a very important mission, Noel.
Noel: Oh, um...right. Th-Thank you!
Celica: You bet'cha!
Nu-13: Nox Nyctores, Bolverk... I will never forgive you! Terminiating target!
Nu-13: Damage critical... I want the Nox Nyctores... Not some doll.
Celica: Did she go...? But she said something about the Nox Nyctores... ...Is that what she's looking for? I wonder why...?
|Stage 6: Kokonoe|
Kokonoe: Celica, I've finally found you. i hope you realize how much trouble you're causing for those who have to follow you.
Celica: Miss Kokonoe... you were searching for me?
Kokonoe: Duh. You're the ace up my sleeve... I managed to pull out from deep within the Boundary. You are still waaay too valuable. To defeat Terumi... and to get us out of this pickle. Now, come back to me... and don't go running off again.
Celica: Miss Kokonoe. You sound a lot like my big sister... BUt I'm sorry... I can't go back.
Kokonoe: I hope you didn't expect me to just accept that answer.
Celica: Hehehe... At least you're nicer about it, Kokonoe. That part is a lot like Mister Jubei.
Kokonoe: Stop talking about my parents... If you won't walk back on your own two feet, then I'll just have to drag you.
Celica: You know, there was something I wanted to ask you too, Kokonoe. If I win, you have to tell me, Professor!
Celica: I wiiiin! You haven't forgotten our promise, have you?
Kokonoe: I don't recall agreeing to it, but whatever... Tell me what you wanna know.
Celica: ...This little girl called the Murakumo was going around collecting Nox Nyctores. If you know why she's doing that, could you tell me?
Kokonoe: I wouldn't say that I know... But I have a pretty good idea. Terumi or Relius probably put her up to it. They're trying to smelt Takemikazuchi.
|Stage 7: Yuuki Terumi|
Terumi: The hell... I didn't think I'd run into you here. Is this what they call a godsend?
Celica: Terumi... I heard from Miss Kokonoe, you intend to create the Takemikazuchi again. Is this true?
Terumi: Huuh!? What's that got to do with you, you piece of trash? You should a stayed in the dumpster where you belong.
Celica: Tell me, Terumi... What are you going to do with the Nox Nyctores?
Terumi: i've had enough of your crap! You don't honestly think I'm going to answer you! Your existence is already pissing me off enough. I think I'll just go ahead and... ...Tear up that pretty face of yours, so I never have to see it again!
Celica: Let's go, Minerva! We can't lose this one...!
Terumi: *pant pant* Pfft... I don't have time for this shit. G'rah! Damn, I feel sick.
Celica: Terumi... You've lost this match!
Terumi: Stay away from me, you piece of shit! Heh... Well, I guess this is sorta interesting too... I'll let you in on a little secret. I'm not the one trying to recreate Takemikazuchi... It's your sister.
Terumi: I've changed my mind. I'll tell you where to find her, so you can ask her yourself... Heh hehehe...!
|Stage 8: Nine the Phantom|
Celica: Sister! I've finally found you!
Nine: Celica... That's my line. I've been searching all over for you...
Celica: Let's cut the act... You need to stop what you're doing. Don't recreate the Takemikazuchi. Please...
Celica: I love all the things that you make, Sis... But that's the one thing that I hate. It scares me. That's something that shouldn't be used. It'll break everyone! All the pretty and important things in this world... It'll destroy them all.
Nine: You're right... That's something that's really tough for you to accept. But don't worry... I have no intent of asking you to make sacrifices. This isn't the age of the Dark War anymore. There's no reason for Takemikazuki to suppress its power! We'll unleash it upon this world!
Celica: I love you, Sister. I really, really do, that's why... ...I need to stop you with everything, I have! Minerva, please help me!
Nine: Stubborn little child... You want to protect this world at the cost of your own life!?
Celica: I don't want to protect it... I just don't want to destroy it! This is the world you fought so hard to protect, Sister...! It's important to you--
Nine: It's NOT important!
Nine: I'm not protecting this world! That's not what I wanted...! This... this...
Nine: You saw it for yourself! You touched the Azure... This world is going to repeat itself, over and over again! Every time history rewinds... We have to witness that hell again! So many people are going to die... The suffering, the pain, it's all going to happen again! Save the world!? Wake up! I'm done benig the gods' plaything! We need to reset this world... and that means destroying it. I'll make sure you never have to suffer again, Celica... Please, understand what I'm doing.
Celica: Thank goodness... You're back to yourself, Sister. You're trying to protect me. Like you always do... Thank you... But I can't allow you to do something so terrifying... ... Like destroy this world. Don't even say that! I love this world... I spent time with you. I became friends with Trinity... ...And Ragna... What's there to hate?
Celica: It's okay... I'm sure Ragna and his friends can heal this world. So, you don't need to suffer any more. Sis... Please. Let's put an end to this...
Jin was seriously injured from his fight against Ragna, and Celica tended to his wounds, staying close to his side. She did her best, but left to report to Kokonoe afterwards, bumping into Tsubaki and suggesting that she visit Jin to cheer him up. She was soon taken inside the Embryo with Minerva. 
She found herself in Orient Town in the 13th Hierarchical City of Kagutsuchi with Minerva. She came across a wanted poster of Ragna, and chirped to Minerva that they would find him and Kokonoe in the city.  Through Celica's direction, they ended up in Bascule where they met Naoto Kurogane, he asked them for directions and described Raquel Alucard to them, although the young mage thought he was describing Rachel. They decided to travel together throughout the city.  She, Naoto, and Minerva were teleported to Ikaruga and heard Nine's voice telling her to kill Izanami to claim her piece of the Azure. Worried for her sister, she immediately went to try and find her. 
Finally arriving at Yabiko, Celica explained to Naoto about Nine and the Dark War. She asked more about who Naoto was looking for, and began to realise that they may not be looking for the same person, and her own careless nature made her lose him in the crowds.  It took her a while to notice she had lost him, but she was soon enough distracted by finding Carl and Nirvana, the former with distorted memories. Because of said memories, Celica accidentally offended the young boy, and he ordered Nirvana to attack, but she relented as she, like Celica, knew the truth. Although upset that she had offended Carl once he left, she went on to try and find Naoto with Minerva reassuring her that she said nothing wrong. 
In Kazamotsu, Celica found Ragna. Reunited, they travelled together to Yabiko to find Kagura, Noel, and Kokonoe. The young mage told him of her dream for everyone to be happy and they eventually found Yabiko together.  Celica went ahead to assess the situation of the people's distorted memories of Ragna, only managing to get inside the branch because of Minerva's directions.  Hibiki found her, and they went together to Kagura's office  – Kokonoe explained to her that she unable to find Celica because of the teleporter malfunctioning due to the mismatched coordinates of the Embryo.  She was upset with her niece's decision to send Tager to capture Ragna.  She reunited with Ragna once he was brought back to the branch, and listened to Kokonoe's explanation of the existence of the Corpus Sepulcro: Requiem, also learning that Nine's transformed her father's workshop into her own. 
She was later part of the strike squadron sent to Nine's workshop. Celica watched as her sister beat Jubei throwing him at her and the others. She listened to her explanation of the world, the Prime Field War, and why she had created Requiem. Celica held Jubei as Ragna fought Nine, and rushed to her sister's side when she was defeated.  Izanami arrived, and began assaulting the group and Celica watched as her sister used the Radiance of Extinguishment to activate Requiem and bind Izanami – she watched as her only sister died saving her, and was teleported out of the workshop using her sorcery to force Rachel into using hers, greatly reducing the time she had left in the world. 
They arrived at the church, although Celica was unconscious. Minerva carried her inside to a bed.  She awoke the following morning and made everyone breakfast and tea despite feeling generally odd.  Celica gave her permission for Minerva to takedown Requiem even if it meant her dying.  She watched the stars with Ragna later the night, and talked about Nine and her sacrifice. The following morning, Celica began to pass on, telling Ragna, Noel, and Jin that she was proud of them all before she finally died. 
- XBlaze Lost: Memories, Chapter 1 – Awakening
- XBlaze Lost: Memories, Chapter 10 – Reunion
- XBlaze Lost: Memories, Chapter 11 – Return to Reality
- XBlaze Lost: Memories, Chapter 24 – Epilogue
- BlazBlue: Phase Shift 1, Chapter 1 - Island of Green Wisdom
- BlazBlue: Phase Shift 1, Chapter 2 - Cat of Crimson Sunset
- BlazBlue: Phase Shift 1, Chapter 4 - Doubt of Yellow Equilibrium
- BlazBlue: Phase Shift 1, Chapter 5 - Night of Black Betrayal
- BlazBlue: Phase Shift 1, Epilogue
- BlazBlue: Phase 0, Chapter 1 - Lost White
- BlazBlue: Phase 0, Chapter 2 - Destructive Black
- BlazBlue: Phase 0, Chapter 3 - Reality's Red
- BlazBlue: Phase 0, Chapter 4 - Chance-met Silver
- BlazBlue: Phase 0, Chapter 5 - Sealed Green
- BlazBlue: Phase 0, Chapter 6 - Promised Azure
- BlazBlue: Phase Shift 2, Chapter 1 - White Blade, A Flower
- BlazBlue: Phase Shift 2, Chapter 2 - Purple Ones, Their Theory
- BlazBlue: Phase Shift 2, Chapter 3 - Scarlet Guardian, the Doll
- BlazBlue: Phase Shift 2, Chapter 4 - Indigo Heart, the Conception
- BlazBlue: Phase Shift 2, Chapter 5 - Black Beast, Reappears
- BlazBlue: Phase Shift 3, Chapter 1 - Battlefield with Blue Sky
- BlazBlue: Phase Shift 3, Chapter 2 – Turbulent Ashen Current
- BlazBlue: Phase Shift 3, Chapter 3 – Copper Catgirl
- BlazBlue: Phase Shift 3, Chapter 4 – Silvery Illusion
- BlazBlue: Phase Shift 3, Chapter 5 – Hope and Despair on the Green Hilltop
- BlazBlue: Phase Shift 4, Chapter 1 - Swirling Tea
- BlazBlue: Phase Shift 4, Chapter 2 – Sweeping Away Crimson Grief
- BlazBlue: Phase Shift 4, Chapter 3 – Demonic Human Weapon
- BlazBlue: Phase Shift 4, Chapter 4 – Azure Wish's Fate
- BlazBlue: Phase Shift 4, Chapter – Colorless Guiding Light
- BlazBlue: Phase 0, Epilogue
- BlazBlue: Chrono Phantasma Official Site (JP), Celica A. Mercury
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 6: Friendship
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 7: Ragna, The Wanderer
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 8: Reunion
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 9: Izayoi
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 10: Brothers
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 11: The Night Before…”
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 12: Uninvited Guest
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 13: Mad Dog
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 14: Inherited Will
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 15: The Truth
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 16: Kushinada's Lynchpin
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 17: Doomsday
- BlazBlue: Chrono Phantasma, Story Mode, Episode 18: Beginning of the End
- BlazBlue: Chrono Phantasma, Story Mode, Epilogue
- BlazBlue: Chrono Phantasma, Story Mode, Sector Seven, Episode 2: Unwavering Feelings
- BlazBlue: Chrono Phantasma, Story Mode, Sector Seven, Episode 3: The Melancholy of Celica
- BlazBlue: Chrono Phantasma, Story Mode, Six Heroes, Episode 2: Year: 2200
- BlazBlue: Chrono Phantasma, Story Mode, Six Heroes, Episode 7: Destined Rendezvous
- BlazBlue: Chrono Phantasma, Story Mode, Six Heroes, Episode 8: Bonds of Fate
- BlazBlue: Central Fiction Consumer Edition Official Site (JP), Story - Celica A. Mercury
- BlazBlue: Central Fiction, Episode 001, Chapter 002 – 003
- BlazBlue: Central Fiction, Episode 002, Chapter 010, Sub Scenario 2
- BlazBlue: Central Fiction, Story Mode, Episode 004, Chapter 026
- BlazBlue: Central Fiction, Story Mode, Episode 005, Chapter 038
- BlazBlue: Central Fiction, Story Mode, Episode 007, Chapter 051
- BlazBlue: Story Mode, Episode 007, Chapter 054
- BlazBlue: Central Fiction, Story Mode, Episode 009, Chapter 064
- BlazBlue: Central Fiction, Story Mode, Episode 009, Chapter 065
- BlazBlue: Central Fiction, Story Mode, Episode 009, Chapter 065
- BlazBlue: Central Fiction, Story Mode, Episode 009, Chapter 067
- BlazBlue: Central Fiction, Story Mode, Episode 009, Chapter 069
- BlazBlue: Central Fiction, Story Mode, Episode 010, Chapter 078
- BlazBlue: Central Fiction, Story Mode, Episode 010, Chapter 081
- BlazBlue: Central Fiction, Story Mode, Episode 010, Chapter 082
- BlazBlue: Central Fiction, Story Mode, Episode 010, Chapter 083
- BlazBlue: Central Fiction, Story Mode, Episode 010, Chapter 085
- BlazBlue: Central Fiction, Story Mode, Episode 010, Chapter 086
- BlazBlue: Central Fiction, Story Mode, Episode 010, Chapter 087
|Other (C-series)||Edgar and Claire Vermillion ·Ellen Nelson · Four · Francis and Rosenne · Lao Jiu · Pakumen & Terumen · Three · Two|
|Remix Heart||Elina · Guardian ·|
|Variable Heart||Julian ·|
|Alternative: Dark War|
|Persona 4 Arena/
|Under Night In-Birth|