Nu-13

Nu-13 is a Murakumo Unit who was sealed in the Sheol Gate. She is a playable character in BlazBlue: Calamity Trigger, reappears in the sequel, BlazBlue: Continuum Shift as Lambda's Unlimited form, and has recently been confirmed to once again appear in the latest game, BlazBlue: Chronophantasma.

Information
She was programmed to terminate anyone she deems as hostile subjects that came near the Gate. Nu-13 is also shown to have a split personality, split between an emotionless girl when around others, and a yandere when around Ragna the Bloodedge, though this may be how she was programmed to act. Nu-13 wants to absorb Ragna and have him join her in destroying the world, because she, too, possesses a piece of the Azure Grimoire (although neither she nor Ragna realized the pieces they possess were actually imitations). When Ragna refuses to join her, she decides to take him by force.

She, as with Noel, was made as a replica of Saya, Ragna and Jin's sister. They seem to share some of Saya's memories, though nothing congruous. In the true ending, she tries to merge with Ragna by falling with him into the Cauldron. However, Noel thwarted her efforts and saved Ragna's life. Nu dies after falling back into the Cauldron and failing to fuse with Ragna.

Continuum Shift
In BlazBlue: Continuum Shift, she is replaced by Lambda-11 of Sector Seven. However, she returns as Lambda's Unlimited form in the console versions. She, in Lambda's body, assists Tager on Kokonoe's orders, though her memories are suppressed. Eventually Hazama coaxes her memories as Nu, causing complications in her programming. Under Phantom's influence, Lambda is forced into a battle against an illusion of Nu in her Story mode, becoming comatose if she loses.

In the True Ending of the story mode, Nu arrives just as Hazama is about to deal the final blow to Ragna. Her memories having fully returned, Nu takes the blow herself to protect him. She collapses into Ragna's arms, saying that she dreamt of him while she was in the Boundary, and that she will always be with him, her body disintegrating. In the process, she gives Ragna her Idea Engine, which allows him to bypass Hazama's negation of the BlazBlue, making even Hazama nervous. After the credits, Relius and Hazama can be seen looking into a cauldron saying "It's amazing how she can regenerate just by will!", hinting that Nu is still alive.

In Continuum Shift, Nu appears in the omake endings in her yandere personality with her body still intact, albeit toned down and changed to that of a preppy fan girl devoted to Ragna.

Chronophantasma
After the events in Calamity Trigger following her battle with Ragna the Bloodedge, she was thought to have perished in the Cauldron alone. Nu is later revived by her own will to fuse with Ragna in a form referred to by Hazama as the "Sword of Hades"; however, she retains her appearance and personality from the previous games. She is re-tuned by Hazama to stand in Ragna's way once again, though somewhat resisting his control in her arcade ending.

Appearance
Nu-13's design is wholly based on the Mecha Musume concept, a design motif that includes 'humanizing' machines or inanimate objects. In the case of Nu, hers is based on swords. When not in battle, she appears as a young girl with sunken red eyes and long silver hair tied into a braid held together by a single blade. She wears a bright jumpsuit and a long flowing cape with red-colored tape seals attached to the end. She wears the Azure Grimoire as an eyepatch that covers her right eye. When assuming battle position, she dons futuristic sword-themed armor that features a set of eight disembodied blades that float behind her in a wing-like formation. She now dons a visor with a singular eye and horns at the end.

In BlazBlue: Calamity Trigger, Noel Vermillion once saw a "younger" version of Nu. She wore a blue dress and had much longer hair, resembling Noel physically. This version is also seen when Nu is affected by Amane's Astral Heat, but she has her eyepatch in this occasion.

Personality
Being a prime field device, Nu's emotions were sealed away, becoming little more than an emotionless machine who kills anyone that obstructs her programming or whom she determines to be hostile. When around Ragna the Bloodedge, however, her personality changes to that of a yandere who is absolutely infatuated with him. In her mind, Nu must have Ragna to herself, and anyone who gets in the way of her love must die.

At heart, however, Nu is a sad and lonely girl who has endured years of nightmarish torture, clinging to her memories of Ragna to give her hope. It is for this reason that she hates humans, and wants to merge with Ragna to form the Black Beast.

In Chronophantasma, Nu's personality is more or less the same as in previous games. However, she seems to have acquired habits from the time her soul inhabited another body, as seen during combos with Sword Summoner; she counts the hits in German, like she used to do as Lambda.

Powers and Abilities
In battle, she summons numerous swords to keep pressure on her opponents from a distance. Her battle appearance even stems from an apparatus, resembling a large sword with a face, that breaks apart to become her armor and weapons.

Nu is a very lethal combatant on the battlefield. As a Murakumo unit, Nu boasts abnormal fighting abilities. She can repair herself and fight in tip-top shape should she sustain enough damage, making her seem almost immortal. Her Drive ability, Sword Summoner comes in the form of controlling the very fabric of space. She can alter gravity, open up rifts, teleport, fly and summon swords to wipe out her opponents with ease. In combat, it is not uncommon to see a flurry of swords materializing out of thin air and disappearing just as quickly, flying and attacking rapidly from many angles at once. Her method of finishing off opponents come in the form of combining her eight blades to create a dimensional rift that summons a gigantic sword to smash her opponents into oblivion. Like Ragna, she possesses the Azure Grimoire, taking on the form of her eyepatch. However, like Ragna's, hers is an imitation as well.

Trivia

 * Nu uses more sexual innuendo than any other character in Calamity Trigger, mostly when speaking to Ragna. Such cases are: (Note: Nu almost always smiles when speaking to Ragna).
 * "You knew what you were doing that time." - Ragna's response is "I told you to shut up!" - "You were smiling."
 * "You slashed me... pierced me all over... when I was completely defenseless!"
 * "Those are one and the same. You know it hurt so much last time...! When you lashed out at me, I thought I was a goner!"
 * "But today's gonna be different. See? I even have a new body, and I can talk."
 * "How would you like it? Gentle? Or a bit more rough perhaps?"
 * "Don't wanna talk, hm? Perhaps you'll open up after something a bit more...physical?"
 * In the Japanese official website for Calamity Trigger's arcade version, Nu's voice actor was listed as "????".
 * Nu's Unlimited form allows her to throw out two swords at a time instead of one, effectively increasing her damage potential. This is carried over to Continuum Shift, where Nu's Unlimited form takes the place of Lambda when selected.
 * In early concept art, the blades which float behind Nu are identical to the white portion of Ragna's sword.
 * Her name Nu comes from the 13th letter in the Greek Alphabet. This is the same applies with the other Murakumo Units.
 * Her number, 13, can also be related with the Death Arcana of the Tarot cards.
 * She seems to have three personalities: the robot which is mostly seen, her insane love for Ragna and a third one seen is one of her story paths and her Arcade ending: a girl who silently and desperately calls for Ragna.
 * In one of her conversations with Ragna, she says she has acquired a body that can talk.
 * Nu's Crest, along with Ragna's Crest, seems to be variations of the Black Beast's Crest, implying the fact that Ragna and Nu need to be fused in the Cauldron in order to the Black Beast can surge.
 * Lambda, Nu, Mu, and Amane have the same command input for each of their Astral Heats.
 * One notable factor about Nu is that she has an Azure Grimore over her eye, though Lambda does not, as proven by the True Ending of Continuum Shift. This could refer to the fact that Lambda does not run on the Azure, but on the Idea Engine instead, or that the Azure Grimore shifts position to the central eye on the visor when the Murakumo Unit is activated.
 * Nu is the only character in Calamity Trigger whose Arcade Mode's Final Boss is Rachel, instead of Ragna or Hakumen.
 * Nu and Noel were featured in a montage of characters who were voiced by their current voice actress, Cristina Valenzuela. The montage was drawn by Alex Ahad, art director from the fighting game Skullgirls.
 * Because of her mecha musume concept, Nu is often compared to Anubis from Zone of the Enders because of her frame, although the function of her "wings" and her coloration give her a greater resemblance to the RX-93-v2 Hi-Nu Gundam from the novel version of Mobile Suit Gundam Char's Counter Attack. It is also worth noting that her predecessor, Lambda, has a black, white and yellow coloration, the same color scheme used by the RX-93 Nu Gundam from the movie which was supposed to be a partially completed mobile suit.
 * Nu's artwork for Chronophantasma is the only artwork to feature Nu in her battle armor, which the previous two feature her with her Nox Nyctores behind her.