Code: Embryo, Lost: Memories
The night Touya Kagari would become involved in the Union conflict, Es and Mei battled a Union whose Drive let him control objects from a distance. Mei warned Es not to charge in blindly but Es ignored her, getting injured in the process. However, Es claimed the damage was minimal and defeated the Union. Mei angrily demanded to know why Es put herself at risk, but Es said that her safety was irrelevant if it meant completing the mission. A frustrated Mei left and told Es to report to the Mitsurugi Agency.
Later that night, Mei arrived alongside Souichiro Unomaru at Touya's house. Mei stared at Touya closely and yelled at him to shut up when he complained. In the car ride away, Mei told Unomaru that she sensed a faint presence of the Azure from Touya. After she complained about their “cooperative relationship” being one for Unomaru's convenience, he gave her all the data he had gathered on Touya. She was shocked to find out that he was a Wadatsumi survivor. 
The next day after school, she approached Touya after hearing he would cooperate with the Mitsurugi Agency. She constantly insulted him while explaining that Unomaru begged her to back up Touya if he decided to join. She then placed the Goofball Proximity Surveyor on him. After explaining that it would let her see whatever he sees and warning him to avoid the Magic Guild, Mei left. 
The next morning, Touya saw Mei on the phone where she was angrily saying she refused to work alongside anyone from the Magic Guild. Mei claimed that she would protect Touya so he shouldn't rely on someone from the Magic Guild and she wouldn't lose. 
That night, she was investigating a Union-related incident when Touya suddenly approached her, causing her to hit him. She got very mad at his continuous apologies and him not seeing her as a noble shrine maiden. Mei decided that he could tag along but told him to keep quiet. She studied Akio Osafune's body and concluded that it was the work of Ripper. After finding the night watchman's body, Touya sensed a Union and warned Es and Mei. Es deflected a thrown knife, but Ripper threw a smoke bomb at them. Mei fired a Shikigami Raven at him and he appeared behind Touya but Es knocked him away. Mei told Es to pursue while she protected Touya, with the two following behind. Learning that Avenge had entered the fray, Mei told Touya to hurry up but he said he couldn't go any faster so Mei just grabbed him and used her powers to fly while carrying him there. When they arrived, Ripper fled and Avenge told them to leave Ripper to him - calling Mei a little girl, much to her anger. She reported to Unomaru about Avenge and told Es to take Touya home. 
Two days later, Unomaru forced her to go to the pool with everyone against her will. She stayed in the kid pool, claiming she could swim but just didn't want to in order to hide her inability to swim. Afterwards, Kuon Glamred Stroheim attempted to speak with her, but Mei quickly became hostile, calling her “witch” and insulting her for being part of the Magic Guild.
On the school roof during lunch Mei overheard Touya, Es and Hinata Himezuru talking and complained about going to school with other people, just wanting to eat her lunch in peace. She then overheard Touya and Kuon talking about anime and accused Kuon of being a fangirl while acting elitist about her anime tastes at the same time. When she overheard that Es watches Sunday morning kids' cartoons, Mei accidentally revealed herself before angrily saying she needed to speak with Es. 
In the bath, Mei sensed the confrontation between Touya, Es, Kuon and Sechs and worried about it. She later called Touya to learn what happened, but got mad when he said he was with Kuon, telling him how the Magic Guild ruined her clan.
Two days later, she approached Touya on the school roof and demanded to know what happened the day before so he told her about the confrontation with Acht. Mei complained about getting even more work to do, wondering why one of the Ten Sages was out in the open. She started an argument with Kuon, revealing that she knew about Elise von Klagen staying with Touya thanks to the G.P.S. Once Kuon left, she told Touya what she initially came to him for; that three more bodies had been found and someone who looked like Akira Kamewari was spotted nearby, although Mei doubted he was responsible. She promised to send out a familiar to search for him. 
That night, she arrives at the Himezuru residence to find the newly-Union Akira attacking Touya and Es. She apologized to Touya, saying that Akira was classified as a Union and she had to detain him. Akira briefly regained his sanity and ran off. Mei noted that he had already progressed through a couple of phases and was upset that she couldn't get through to Unomaru. Elise introduced herself to Mei and Mei was taken aback by how polite she was. Mei performed first aid on Touya, Hinata and Es but said Es was in bad shape. Mei used a special charm specifically for her, which she hoped would repair most of the damage even if it couldn't fully heal her. Mei explained to Kuon that most of the damage was from deterioration since Es normally returned to the Mitsurugi Agency headquarters every two days for treatment, but hadn't gone in a while. While Mei did not know what Es was, she speculated that she was a living doll. Kuon was shocked to find out that a Homunculus existed but thanked Mei for being there to help, saying there's nothing sadder than losing a family member. Mei, remembering that Kuon just lost her father, confided in her that she also lost her mother, Sui Amanohokosaka, during the Wadatsumi Incident and could understand her pain. Mei then discussed with Kuon and Elise how unnatural it was for Akira to already be in phase three and what the Ten Sages were planning, specifically to push Touya over the edge. Mei told them that she heard a strange Discover Call from Touya. She confirmed that he wasn't a Union but was worried about the Discover Call's meaning.
The next day, she received word that Es would be taking a three-hour break and headed to the Himezuru residence to watch Touya. She caught him trying to sneak out but decided to accompany Touya somewhere as long as it's close by and he chose Maha Raja. Upon meeting Ringo Akagi, Mei initially assumed her to be Zwei of the Ten Sages, but concluded there's no way she'd be working at a curry restaurant. Ringo said she had no idea what Mei was talking about. She then told Touya about the history of her clan; that they had been guarding the “Legendary Lands” since before recorded history but when the Magic Guild brought the clan to ruin, they sold the Legendary Lands to the Takamagahara Organization for a lot of money. After the Wadatsumi Incident, Takamagahara disbanded and the Mitsurugi Agency came in to support the Amanohokosaka clan in exchange for using the shrine maiden's powers, which was why Mei had to listen to Unomaru. 
The next day inside the Shin Yokozaki University Hospital, Mei ran into Yuki Himezuru after visiting her father. Mei asked Yuki to explain the situation to Touya when he arrived. Mei took Yuki to the roof and told her she could get in touch with Avenge for her. Mei promised to tell Yuki what she knew, but warned her that it involved the incident 13 years ago. Mei told Yuki the story behind her parents' murder, how Avenge saved her and that Ripper survived, but it was covered up since he was a Union. Mei then asked about Hinata, wanting to know who she was since Yuki was an only child. However, Yuki said that Hinata was absolutely her younger sister, regardless of blood connections. She then told Mei the story of how she met Hinata. Mei warned Yuki that she shouldn't meet with Avenge but Yuki said she had to in order to learn about Hinata's past. Mei relented and said she'd get in touch with him for her. 
That evening, she received word that Hinata had been kidnapped by Ripper and went to get Es from the Mitsurugi Agency's headquarters, telling her they needed to hurry. In the car, the two discussed what they knew about Ripper. Mei found them on a roof in the Restricted Ward and they headed over. They saw Hinata falling and Mei used her magic to help Es catch Hinata. While Touya was going berserk after unleashing the power of the Origin of the Grimoire, she healed an injured Kuon with her charms and showed Touya that Es saved Hinata, calming him down.  Mei tries to get Touya to wake up and told Es to take Hinata back to the Himezuru residence. She was angry that the G.P.S. ended up being totally useless. She told Kuon that Touya unleashed the power of the Black Beast. Drei and Sechs then arrived and Sechs told them that they needed the power of the Black Beast to destroy the Embryo. Drei told them that Unomaru was planning on using the Embryo to control the minds of everyone in the world. He warned Kuon and Mei not to get in their way or they would return everything to seithr and that all that mattered was the future Sechs was trying to create. Sechs and Drei then disappeared. Once Touya woke up, Mei promised to tell him and Kuon everything she knew but suggested they return to the Himezuru residence since it was too dangerous where they were.
Back at the Himezuru residence, Mei told Touya and Kuon and about the Gate of Sheol underneath the Wadatsumi Research Facility, about the Amanohokosaka's history guarding the Gate and that the first Azure Shrine Maiden stopped the Black Beast from emerging by luring it back into the Gate and sealing both of them inside it. Touya had doubts that Unomaru was planning what the Ten Sages said he was, which angered Kuon. Mei told Kuon not to put too much faith in the Ten Sages words and Kuon countered that she was saying they couldn't trust Mei because she's part of the Mitsurugi Agency. Mei said her family was basically being held hostage and Kuon wouldn't be able to act if she was in the same situation. Kuon said she came fully prepared to kill her own brother, but Mei didn't believe that. Mei said she had plans to eventually reclaim Wadatsumi, which Kuon didn't accept. Kuon then left, saying she's going to speak to Sechs one more time and that she'd probably never return to the Himezuru residence. Mei told Touya that she would be guarding Touya from then on in case the Grimoire went berserk again, but he was worried about Kuon and ran off. Mei got angry and said it's not her problem anymore. After Es came out and managed to calm her down, Mei explained to Es about what happened. Es then convinced Mei that Kuon actually did trust Mei, surprising her that Es was acting as the voice of reason. She then received a call from Unomaru, who had her tell Es to return to the Mitsurugi Agency. Mei warned Es about the Ten Sages, saying Unomaru was planning to control the minds of all mankind and said Es would have to choose a side eventually. 
Touya was classified as a high-risk Union that needed to be taken in and Mei was put in charge of the unit searching for him. She found him and Es together. Touya told her about Es's promise to kill him and Es said she knew she would die for betraying the Mitsurugi Agency, which caused Mei to quit the Agency in frustration, saying the two needed to care about their own lives more and consider how those close to them would feel if they died. Mei told Touya she would find Kuon so he should focus on escaping. Mei covered for them with a smoke bomb and they escaped underground. Mei called Unomaru, demanding to know why she lost command of the unit but Unomaru said it was orders from the higher ups and hung up. Mei knew he's lying but was glad she could move more freely and prepared to meet up with Touya and Es. 
At some point she encountered Avenge and asked him to “go save that idiot.” She then met up with Touya and Es as they emerged from the sewers, saying she still hadn't found Kuon. Mei yelled at them for smelling and said she had a spare set of clothes for Es. Es thanked Mei, which embarrassed her. Mei told Touya to go home and get a change of clothes and when Touya asked if he would be safe there, she told him that Elise sent out a false lead that Touya was on a bullet train away from Shin Yokozaki City. Touya wanted to tell Mei about the T-System and the Ten Sages but Mei revealed she had Avenge put a wiretap on him and already knew about it. Touya, Es and Mei decided to return to the Himezuru residence and were greeted by Hinata. Mei asked Hinata if anything out of the ordinary happened but Hinata said she'd been sleeping until recently. Mei then asked her if Kuon returned and Hinata said she was upstairs. Hinata then realized she promised Kuon not to tell Mei about her return and begged Mei to pretend she didn't hear but Mei refused. Hinata was afraid that the two would start fighting but Es said it's okay because Mei and Kuon were friends, which took Mei aback. Mei went upstairs and met with Touya, telling him about Kuon while insulting her. Kuon told Touya and Mei to meet her downstairs since she had important information from Elise. Hinata offered them tea and Mei said how good it is, but Kuon got upset when Mei called it “cheap.” After Hinata left, Kuon read a letter from Elise that contained her findings about the Wadatsumi Incident. She discovered that Unomaru was a survivor of the incident and that he was not working to treat the Unions he captured, but rather to gather their crystals so he can refine the Embryo. She also found that TOi was powered by the T-System and was created to be a high-level information control system. Learning of Unomaru's corruptions, Mei planned to take him down so that the Mitsurugi Agency would give her control of the anti-Union activities in Shin Yokozaki City. They figured out that Unomaru was likely at the Wadatsumi Research Facility attempting to complete the T-System. Mei said Touya should stay behind because of the Grimoire and because it's too dangerous but Touya insisted he had something he needed to ask Unomaru. Kuon said they should bring Touya along and promised to kill him if he lost control so Mei agreed, but said she'd send him home if things got too dangerous. They then discussed that they needed to deal with the Ten Sages, Mei revealing that Avenge told her that he killed Drei. Mei theorized that the Origin of the Grimoire was the only thing that could destroy the Embryo and the Ten Sages had been trying to cause Touya to activate it for that reason. Mei asked if they had anything they needed to do before they headed out and Es asked for pudding so Mei begrudgingly said they'd wait until Hinata returned. After Touya got off the phone with Yuki, he told Kuon and Mei that Akira was going to be all right. Kuon was relieved but Mei said she found his ability to survive gross like an insect. Just as Mei complained about Hinata taking a long time to get back, she arrived with pudding. 
Arriving at the Restricted Ward, Mei found it odd that there was no one there. Es didn't detect any human presence inside and said if they were going to go inside they should do it then. Inside, Touya recalled how he first met Es. This caused Kuon and Mei to get in another fight, with Mei saying she couldn't believe she was working alongside someone from the Magic Guild. Kuon promised that she would force the Magic Guild to change its ways once she got back to Ishana but Mei must reclaim Wadatsumi in exchange. Mei accepted and they approached the wall around the Wadatsumi Research Facility. They were suddenly attacked by Acht's Ice magic. Es deflected all of the attacks and Acht remarked that she hoped to kill at least one of them with that attack. Acht said she had no idea where Sechs was and was no longer involved with him; she just wanted to go crazy. Acht said that they must defeat her in order to go on. She told Touya to go away since she didn't want to deal with him, but then said she's just kidding and attempted to kill him. However, Es protected him. Acht called Touya pathetic for always having others protect him. She then attacked him again but was intercepted by Mei, who told Touya to go home and he ran off. As Kuon, Es and Mei discussed what to do with Touya, Acht attacked again but got blocked by Kuon's Fire magic. Kuon told Es to go with Touya and leave Acht to her and Mei. Kuon then created a large explosion that blinded Acht, allowing Es to get past her. Mei thought Kuon was crazy, since they couldn't hurt Acht thanks to her Drive. Kuon planned to use the Sealed Spear: Izayoi, but Mei told her not to use it except as a last resort and that the two of them would defeat Acht together. Acht overwhelmed Kuon with her Ice magic, claiming she could teach Kuon a few things. Mei tried to attack with Lightning magic but got blocked as well. Kuon and Mei then both fired at Acht simultaneously, forcing her to activate her Drive to negate their attacks. As a “prize” for forcing her to use her Drive, Acht told them more about the Embryo; that the Embryo already existed in an incomplete state that both existed and didn't exist. Acht asked Mei how to destroy something like that and Mei said with the Origin of the Grimoire, but Acht said that was wrong. Acht then told her that they needed to first complete the Embryo and only the Grimoire could refine it. Kuon wondered if Sechs learned all that from the crystal, but Acht said story time was over and renewed her attack. Mei said they were in trouble if Touya and Es decided to go on ahead of them so Kuon said she had no choice but to use the Izayoi. Mei responded that she couldn't afford to let Kuon use it and had a secret weapon, the Goofball Proximity Surveyor. Mei then attacked Acht again but snuck in the G.P.S. in the confusion, negating Acht's Drive and giving Kuon the opportunity to unleash her full power against Acht. However, it wasn't enough to put Acht down, but it did cause her crystal to progress a phase. Acht retaliated by launching a large iceberg at the two, which Kuon barely managed to destroy. At that point, Acht had reached phase six and devolved to the point where she was screaming about how they were enemies who she had to kill, creating another giant iceberg. Mei told Kuon that she needed to stop firing such large spells or she'd kill herself. Kuon said she'd never be able to live with herself if she ran. She also said she didn't believe that Acht abandoned Sechs and she was doing this out of loyalty. Kuon felt she had to respect her resolve. Kuon and Mei put all of their power into one combined spell, which pushed Acht's crystal over the edge. In her last moments, Acht asked if Sechs was there and tried to tell him she loved him before disappearing into seithr, leaving behind only her crystal. Kuon and Mei then went off to find Touya and Es. 
Kuon and Mei arrived to back Es up, who was fighting three Es-N units. Es told them that the Es-N units had their combat data and could predict their moves as well as that Touya went on ahead. Mei and Kuon said that's bad since the Grimoire was needed to refine the Embryo. They then told Es to go on ahead and leave the Es-N units to them. During the battle, they felt an earthquake and realized the refinement must have started. The Es-N units continued their assault and Kuon said they'd have to leave everything to Es.
Kuon and Mei managed to defeat the Es-N units and reached the core of the T-System, where they saved Es and Touya from Sechs, but were quickly defeated by him.
One month after the Embryo incident, Touya, Kuon and Mei were chasing a Union and Touya could tell they were in phase four based just on their Discover Call. They found him and noticed he was acting unnatural and his clothes were damaged. Not wanting to prolong the fight since they're not in the Restricted Ward, Touya activated XBlaze. Touya asked Mei if she could use a spell to restrict the Union's movement since he didn't want to hurt him. Together the three managed to subdue the Union. Mei said she's glad she had Touya and Kuon's help and Kuon realized that it meant Mei was understaffed. Mei then told them that she was reprogramming the last Es-N unit to work for them, but was having trouble switching its power source from crystals to electricity. Mei said that Es-N would probably be less efficient like that, but was sure she could compensate with her magic. Kuon made fun of Mei's style for thinking a robot familiar was cool and the two got into an argument. Touya tried to break it up, but the two insisted they were having a normal conversation.
One month later, Mei arrived in Touya's classroom and greeted him and Hinata, apologizing for being late. Touya said he needed to get going and Hinata wished him luck with his new job, saying it's a shame Maha Raja closed so suddenly. Touya tried to say that it wasn't a job but decided it's close enough. Hinata then told Mei that she received mail from Kuon, saying that she made it back to Ishana safely and to tell Mei that she would keep her promise on the honor of the true Ten Sages. It also said that, due to Elise's insistence, they would be back in Japan soon. Mei said that meant they'd just have to work even harder. Mei then told Touya to move out and not to fall behind. In the Restricted Ward, Touya asked about the Union they were supposed to be chasing but Mei said that Es-N already took care of it so Touya said he'd see her at school. 
Some time after the Embryo Incident, Mei remained within Sleipnir and continued to hunt down Unions with Touya and Kuon. One day, the three of them swiftly apprehended a Phase 4 Union; afterwards, Mei revealed that she was working on the Es-N and attempting to recalibrate them using electricity and magic.  A few days afterwards, Mei went to another town to pick up some special Japanese pastries for the group so that they could celebrate Kuon's last day in Japan. At the Himezuru residence, she presented these pastries, getting teased by both Kuon and Hinata for going through the special effort. Touya asked Mei for some cooperation in trying to reclaim his lost memories, and she agreed to lend him the assistance of Avenge, who she had recently contracted for the Amanohokosaka Clan while she was short of staff.
Mei spent the next couple of weeks combing through Unomaru's office and data for anything that might be relevant to Touya's request. She eventually found his private journal, and went to the Himezuru residence to share her good news. There, she found that Ringo had subjected Touya to 10 days of non-stop curry. Regardless, she revealed her information to him and listened when Elise and Kuon rang him to reveal what they had uncovered. At his insistence, Mei handed Touya the keycard to Unomaru's office and later told Avenge to meet him there. Mei was able to crack the cipher on Unomaru's journal, where she made a startling revelation about Touya's existence. She called him to Unomaru's office and made him promise that he would always be “Touya Kagari” before revealing its contents to him. Mei told Touya that he was really the Origin of the Grimoire that was given shape and form by the Embryo's power, and that the original Touya Kagari was a six-year-old Drive-Union who was killed by his own Drive. After revealing this to him, she left.
Mei eventually discovered more information, this time it was documents left behind by Ryouko Kagari as well as a flashdrive. She read them and learned about her relationship with Mei's own mother, Sui. Mei called Touya and the two met again in Unomaru's old lab. Here, she told him about the contents of the documents, and how the original Touya passed away. After listening to Touya talk about his desire to officially join Sleipnir, Mei accepted, but did remind him that she was still his superior officer. After handing him the flashdrive, Mei remarked that maybe they were always fated to meet in order to continue their mother's work. 
Within the Restricted Ward, Touya would eventually come across a Union named Freaks. This Union was too strong for Touya, Mei, Kuon, and Elise, and managed to kill them all. Es, who watched silently from within the World of Tsukuyomi, could not let them die in vain. She rewound time, but without a variable factor, the event was always destined to happen again and again. This changed when Konoe A. Mercury intervened, repowering the Embryo and allowing Nobody to create a human version of Es in Shin Yokozaki at least a few days before the deaths would occur. 
Mei visited the Himezuru residence to relay some news to Touya. When she arrived, she saw Es in their home. Es, who had been resurrected, remembered some part of Mei, but the young shrine maiden still had her memories altered, so was unable to remember her. Mei took Touya outside to talk about work since she viewed Es as a civilian who could not get involved with their line of work. After their work finished, another Union appeared, meaning that the pair had to work late into the night. A couple of days later while in Akihabara, Mei saw Kuon and Elise reading manga.
Es was held a welcoming party by Touya, Hinata, and Yuki. Mei was among those invited, and she took pleasure in teasing Kuon and Elise for their supposed “mission” in Japan actually being them taking a vacation to read manga; she was, however, asked to stop by Hinata. The following day, Mei called Touya, Kuon, and Elise to explain that a Union was running rampant through Shin Yokozaki, and was responsible for a string of incidents being referred to as the ‘vampire incidents'. Later that same day, she heard from Kuon and Elise that the leaders of the Magic Guild had been murdered by a Union known only as Freaks. Their actual mission was to hunt him down, as they knew he was in Shin Yokozaki, and they needed the aide of Mei and Touya. Mei later told Touya this information, where he revealed that he believed Freaks could be a Strange Red since he had been hearing two Discover Calls chime in at similar times. 
The following day, Mei met up with Touya, Kuon, and Elise to discuss the apprehension of Freaks.  She later received a call from Yuki that explained that Es had followed Touya into the Restricted Ward. She hurried as soon as she could. When she arrived, Touya was already in trouble. Mei launched her spells at Freaks, but he cut through them all. Mei was cut deep several times by Freaks attacks and was saved by the arrival of Kuon and Elise. Mei soon fainted from the pain.  When she awoke, the battle was still raging. Mei joined Elise and Kuon in firing as many spells as they could at the Union. Through a combined attack by Touya and Es, Freaks was finally killed. 
Weeks after Freaks was defeated, Es moved into Mei's house. Together with Es and Touya, Mei formed a new organization that focused on destroying cauldrons worldwide.
- XBlaze Code: Embryo, Episode 1
- XBlaze Code: Embryo, Episode 2
- XBlaze Code: Embryo, Episode 3
- XBlaze Code: Embryo, Episode 4
- XBlaze Code: Embryo, Episode 5
- XBlaze Code: Embryo, Es & Hinata Route Episode 6
- XBlaze Code: Embryo, Es & Hinata Route Episode 7
- XBlaze Lost: Memories, Green Stone Sub Memory 03
- XBlaze Code: Embryo, Es & Hinata Route Episode 8
- XBlaze Lost: Memories, Azure Main Memory 04
- XBlaze Code: Embryo, Es & Hinata Route Episode 9
- XBlaze Code: Embryo, Es Route Episode 10
- XBlaze Code: Embryo, Es Route Episode 11
- XBlaze Code: Embryo, Es Route Episode 12
- XBlaze Lost: Memories, Black Stone Sub Memory – Phantom Boy, 01 Part A
- XBlaze Lost: Memories, Black Stone Sub Memory – Cooperation, 01 Part B
- XBlaze Lost: Memories, Black Stone Sub Memory – Progression, 02 Part A
- XBlaze Lost: Memories, Black Stone Sub Memory – “Touya Kagari” 02 Part B
- XBlaze Lost: Memories, Black Stone Sub Memory – Shared Feelings 03 Part B
- XBlaze Lost: Memories, Chapter 12 – For a Friend
- XBlaze Lost: Memories, Chapter 15A – Connection
- XBlaze Lost: Memories, Chapter 17A – Welcome Party
- XBlaze Lost: Memories, Chapter 18A – A Boy and His Cat
- XBlaze Lost: Memories, Chapter 19A – Beginning
- XBlaze Lost: Memories, Chapter 20A – To Tempt the Azure Fate I
- XBlaze Lost: Memories, Chapter 23 – World of Possibilities
- XBlaze Lost: Memories, Chapter 23 – World of Possibilities
|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|
|Crossover Characters (BBTAG)|
|Persona 4 Arena/
|Under Night In-Birth|