an evil sign
Now in a laboratory, Nu was connected to several cords, including one large one in her eye, each injecting seithr into her body. Scientists meddled with constantly raised the levels during the process of this. Nu's body began to spasm as she came to life, and the scientists declared that their job was complete. They decided on the schedule for her to be delivered to Relius Clover, while discussing how she was made by both him and Sector Seven. However, they were interrupted in their discussions by Hazama, who claimed to have an order from the Imperator to pick Nu up personally.
Hazama asked to see the unit for himself, which the lead scientist agreed to. He took Hazama to the chamber she was contained in. He touched her and marvelled at their work, proclaiming that she truly was the thirteenth unit. However, after the scientist left, he began to mock Nu, demanding she wake up. Her eyelids began to flutter in response to his words.
A young girl who appeared from the "Cauldron" buried deep within Kagutsuchi. Nothing about her appearance suggests who she may be.
|Stage IX: Taokaka|
Nu-13: Target... identify... analyze... Unknown... unknown... A defect in the system code has occurred... Who... are you?
Taokaka: Tao is Tao. Are you flappy-flap? What do you want from meow?
Nu-13: Status: unknown. Answer: existence, Nu.
Taokaka: I don't understand a word you're saying, meow. But you wanna play with me!? I'm ready! *whoosh* *whoosh*
Nu-13: Target... battle... status... response... Target has been recognized as a hostile organism... Error... Appropriate action based on autonomous behavior has been activated.
Nu-13: Elimination of the target has been confirmed. Unknown... Status: unknown...
|Stage X: Rachel Alucard|
Rachel: Were you lured here by the aroma of tea? Gii, we have a guest. She will require a cup of tea.
Nu-13: Status: unknown... Existence: unknown... Current condition: obstacle identified. Shifting to recovery mode... failed...
Rachel: So, this is your wish... playing with a free-spirited cat and taking a walk under the clear sky. A pathetic doll with dreams that will never come true.
Nu-13: Status: unknown... unknown...
Rachel: Unknown? Oh dear me, no. Try "worry".
Nu-13: Response... search: "worry". 0 results returned...
Rachel: This is called a "dream": a manifestation of your deepest desires. But I'm afraid this is not the sort of dream where you are permitted to wander. It is time to wake up, little doll.
Rachel: This was your dream, but now it has ended.
|-the Calamity Trigger-|
Nu-13: ... Ragna... Where are you?
When Noel Vermillion came into the presence of the cauldron inside Kagutsuchi, Nu descended from it. She immediately identified Noel as the twelfth unit, the long missing Mu-12. She equipped Murakumo and battled against Noel and her Arcus Diabolus: Bolverk. Eventually, the fight ended with Nu victorious, ready to kill her predecessor; the conclusion was better than she could have hoped for, as Ragna lept in front of the blade meant to kill Noel. Nu, ecstatic that Ragna had finally arrived, began to tell him all about her dreams of seeing him, and ripped her blades out of him. The two battled, and again, Nu emerged victorious. She stabbed him again, and told Ragna about how much she wanted to stay by his side. The pair began to fall into the cauldron, to become a Black Beast, but Noel managed to barely save Ragna with an outstretched hand, and Nu fell into the cauldron to die alone. 
Though she had died, there was a small duration where Nu's soul had yet to reach the Azure. Kokonoe snapped up the soul and put it into Lambda-11, Nu's sister unit. Nu's memories were sealed away, but she was able to see Ragna one more time before Lambda herself died. As Nu has a life link with Ragna, she began to reconstruct herself in the Boundary shortly afterwards. 
Nu-13, who resurrected by her own will in order to fuse with Ragna. Hazama calls her the "Sword of Hades." Rebuilt by Hazama, she once again stands before Ragna.
Hazama and Terumi were given charge over preparing Nu after she rebooted. In the February of 2200AD, Phantom teleported Ragna to her location in the Grave Marker of Bases and the two battled. Nu landed a serious wound on Ragna and Izanami undid the event using Phenomenon Intervention. Ragna was still wounded from the battle even though it had not happened.
Nu later entered the Realm alongside Hazama and Yuuki Terumi. She battled against Noel, who had accepted her identity as Mu-12, leading to the first known clash between the two Lux Sanctus: Murakumo's. Nu's primary objective here was to Observe and synchronize with Noel's status as the Eye of the Azure, being partially successful before retreating. She stood by Hazama and Terumi as they watched over the Battle of Ragna the Bloodedge.
Alongside Relius, Ignis Clover, and Litchi Faye-Ling, Nu made her way to the 8th Hierarchical City of Wadatsumi where she further synchronized with Noel. She was repelled by the Ex Machina: Minerva but had still completed her objective, and returned to Terumi above the Monolith in the 5th Hierarchical City of Ibukido so she could open the gates to the Nemesis Horizon. After doing so and summoning the Amaterasu Unit into the world, Nu merged with the Gigant: Take-Mikazuchi, which Izanami had summoned from its orbit around the planet.
Ragna, Minerva, and Celica found Nu inside the distorted time-space of Take-Mikazuchi. She told Ragna that she had Noel's memories and that both Noel and Hazama were supposed to fuse to become a Black Beast. However, her twisted personality around Ragna came back and the two fought. Nu lost, knocked unconscious by the strength of the Grim Reaper. He then carried her outside of the Nox Nyctores. She woke up soon after and stabbed Ragna; after Ragna's Azure Grimoire went berserk, Nu disappeared.
Nu found Azrael, Litchi Faye-Ling, Kagura Mutsuki, and Iron Tager together in Downtown. Her mission was to retrieve Litchi and fought against her, winning but no succeeding in her mission because of the interference of Tager and Kokonoe, who teleported the group, bar Azrael, away. Nu was left with Azrael but had no will to fight him – Hazama interrupted the two, asking if one was going to propose to the other. 
A young girl who appeared from the "Cauldron" buried deep within Kagutsuchi. She is a Boundary Interface Prime Field Device fitted with the Phenomenon Weapon "Lux Sanctus: Murakumo." She has appeared once again in order to fuse with Ragna, but things seem a little different from before.
Cast into the Embryo, Nu's memories were changed so that she believed it was 12/31/2199. She also became one of the chosen. She woke up in Kagutsuchi near the cauldron, being awoken by Noel. Despite being knocked to the floor, she continued her assault, only being stopped by Ragna.  She lost to him, something she didn't think possible, but instead of killing her, the Grim Reaper offered to save her, only being unable to as he was teleported away by Nine the Phantom.  She was transported to Ikaruga and told by Nine to kill Izanami so she could claim her piece of the Azure and have her wishes come true. Relius had also ordered her to start hunting for the Nox Nyctores' and began with the Arma Reboare: Muchourin, finding Platinum the Trinity but being able to keep track of her due to the latter's fluctuating existence. 
She later found Bang Shishigami, the wielder of the Phoenix: Rettenjo and began fighting him until she was interrupted by Nine. She fought back against both, insanely muttering that the Nox was hers and hers alone; despite this, Bang still managed to flee.  While searching for the ninja, she was attacked by Arakune who wanted her Murakumo. She was saved by Relius, who conducted repairs on her, and she allowed it.  Nu later followed Izanami into Nine's workshop and nearly assaulted the witch had she not been stopped by Jubei. The two fought until the Corpus Sepulcro: Requiem froze the area in space-time. 
When Nu awoke, she was still fighting Jubei, although this time above ground and near the Amaterasu Unit. Intent on destroying it, she fought Jubei and then eventually both Hakumen and Izayoi. She beat the both of them, only being stopped by Ragna, who she revealed to that she had absorbed the core of Gigant: Take-Mikazuchi. When defeated, Nu was knocked unconscious but was forced to awaken by Terumi who sent her insane and broke her soul. Nu lashed out, nearly killing Tsubaki, a blow that was defended by Hakumen – she fought the leader of the Six Heroes, being not only defeated, but knocked unconscious.  She was watched over by Tsubaki and Jubei until all three of them dissolved into seithr.
In the new world created by Ragna, Nu was left in a catatonic state. She now lives bedridden inside a church with Noel and Lambda as her carers. 
- BlazBlue: Calamity Trigger Official Site (JP), ν -13-
- BlazBlue: Calamity Trigger - Part 2, Chapter 5 - Calamity Trigger - Successor to the Azure
- BlazBlue: Continuum Shift, Story Mode, True Ending
- BlazBlue: Chrono Phantasma Official Site (JP), ν -13-
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 7: Ragna, The Wanderer
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 12: Uninvited Guest
- BlazBlue: Chrono Phantasma, Story Mode, Chrono Phantasma, Episode 14: Inherited Will
- 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, Sector Seven, Episode 7: Looming Darkness
- BlazBlue: Central Fiction Consumer Edition Official Site (JP), Story - ν -13-
- BlazBlue: Central Fiction, Story Mode, Episode 004, Chapter 031
- BlazBlue: Central Fiction, Story Mode, Episode 004, Chapter 033
- BlazBlue: Central Fiction, Story Mode, Episode 006, Chapter 045
- BlazBlue: Central Fiction, Story Mode, Episode 006, Episode 050, Sub Scenario 1
- BlazBlue: Central Fiction, Story Mode, Episode 007, Chapter 051, Sub Scenario 1
- BlazBlue: Central Fiction, Story Mode, Episode 010, Chapter 082
- BlazBlue: Central Fiction, Story Mode, Episode 011, Chapter 092
- BlazBlue: Central Fiction, Story Mode, Episode 012, Chapter 100