Nu-13

"Ragna... I knew you would come for me! Now we can finally be together..."

- Nu-13

Nu-13 is the final boss of the video game BlazBlue: Calamity Trigger and she is one of the clones of Saya along with Noel Vermillion and Lambda. She was designed to be yandere towards Ragna and wants to become one with him to become the Black Beast.

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 also knows Hakumen, recognizing him as a "Sankishin Unit".

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'll 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, Nu was thought to have perished in the Cauldron alone. She is later revived by her own will to fuse with Ragna in a form referred to by Hazama as the "Sword of Izanami". 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.

During the course of her readjustments and tuning, Hazama makes Nu fight against illusions of Ragna the Bloodedge and Mu-12. After she defeats them, Hazama is amazed at how Nu, who was still in readjustment state, was able to defeat Mu-12. Hazama then commands Nu to absorb the defeated illusion of Mu-12, but it suddenly disappears. He becomes angry at this sudden happening and blames it on Rachel Alucard. Hazama concludes that he needs to fuse them in reality instead, then tells Nu to follow him so that he can adjust her in the underground, where she is taken to the Cauldron in the Gate. Afterwards, Nu is seen smiling and happy about being able to meet Ragna soon.

Later on, after Hazama makes Phantom teleport Ragna into the Grave Marker of Bases, he then declares the start of the "Heart-Warming Reunion" and makes Nu descend to Ragna. Hazama then tells Ragna to kill each other with Nu, the Sword of Izanami, for her adjustments.

After Nu recognizes Ragna, she laughs and tells Ragna that they should start killing each other. Nu and Ragna fights, but because Ragna wasn't giving his all, she tells him that he isn't doing enough for her, which forces Ragna to activate his Azure Grimoire. However, a Dimensional Interference starts in the area, and Ragna becomes unable to activate his BlazBlue. After Ragna is surprised at the fact such a huge level of Dimensional Interference is happening, Hazama tells Ragna that it is possible thanks to the Imperator's power. After Ragna tries to attack Hazama, he makes Nu attack Ragna, where she injures him. Nu tells Ragna not to take his attention elsewhere and that he should only look at her. Hazama then declares that the Banquet is starting and tells Nu and Ragna to continue killing each other as their "song" will open the Nemesis Horizon.

It is seen later that after the Dimensional Interference, the injury that Nu had given to Ragna was recorded into his Azure Grimoire, and that injury had opened up afterwards.

Later after Noel Vermillion obtained control over her power as Mu-12, Hazama ambushes her and makes Nu "observe" her and fight against her. After the fight, Nu retreats from the area.

When Litchi Faye-Ling goes to Ikaruga to find Kokonoe and waits with Iron Tager, Azrael coincidentally appears and Nu appears to attack Litchi under Hazama's order. Nu easily defeats Litchi but is unable to finish her off because Kagura Mutsuki and Tager interferes and escapes with her, where Nu is left alone with the disappointed Azrael. Azrael is unable to fight against Nu because she had no fighting intents against him.

Later during the battle in the Colosseum, Nu is seen standing with Hazama while he talks to Izanami. Afterwards, Hazama tells Nu to follow him so he can give adjustments to her.

When Ragna, Noel, and Celica visit Asphyxia in order to obtain the Kushinada's Lynchpin and was about to receive Bang Shishigami's help, Relius, Nu, and Litchi assault them to stop them from activating the Lynchpin. Nu attacks Noel, and starts synchronization with her. They both enter an empty white space where Nu and Noel see each other in a mirror. After Noel declares that Nu is Noel Vermillion due to being pulled into the situation, the synchronization succeeds.

After coming back to reality, Nu tells Relius that the synchronization with Noel had finished. It is revealed that due to the synchronization, Nu had also become a Successor of the Azure. Relius then commands Nu to kill Noel since she is of no use anymore. Nu then attacks Noel, where Celica A. Mercury tries to protect her, which makes Nu attack both of them but is blocked by Ex Machina: Minerva from harming them. Afterwards, Relius commands Nu to go to where Hazama is. Ragna tells Nu to stop, but she ignores him and leaves.

Nu then arrives below the entrance of Nemesis Horizon. Hazama commands Nu to open it and pull Master Unit Amaterasu out of it. Nu activates her Azure Grimoire and prays as the Successor of the Azure to tell Master Unit Amaterasu to appear before her. The Nemesis Horizon then opens and Amaterasu becomes summoned into reality.

After Take-Mikazuchi is summoned onto the earth, Izanami commands Nu to fuse with Take-Mikazuchi in order to control it.

After Ragna defeats Take-Mikazuchi and enters it with Celica, Nu appears in front of them. Nu then starts speaking in the same way of how Noel speaks. When Celica and Ragna could not tell how fast or slow the time is flowing inside, Nu tells them that because of Celica, the time inside Take-Mikazuchi is accelerating. After the scenery inside Take-Mikazuchi appears, it is shown that they were inside Ishana, which was the last scene the current Celica had seen before she had come to the future. Nu tells Ragna that she was waiting for Ragna for a long time and was worried because he wasn't showing up. Ragna tells Nu to stop with her current way of speaking like Noel, which makes Nu tell him that he is being mean because she is currently also Noel Vermillion, which Ragna denies and tells her that she is Nu.

Nu then tells Ragna that through the synchronization with Noel, she found out that the 5th Hierarchical City of Ibukido was the place where Noel Vermillion was supposed to disappear. She tells him that on the day Ibukido had perished, Noel was being smelted as a material to be used for the creation of a Black Beast, in order for Sector Seven to win the war against the Novus Orbis Librarium. Nu then asks Ragna how a Black Beast is created, and tells him that they are created through the fusion of an Azure Grimoire and a Murakumo Unit. Ragna then asks Nu how Sector Seven knew this, where Nu tells him that someone had told them the method, which happened to be Relius Clover. Nu tells Ragna that the Murakumo Unit that was to be used as a material for the creation of a Black Beast was Noel and asks Ragna who he thinks the owner of the Azure Grimoire was at the time, where Ragna realizes that it was Yūki Terumi. Nu reveals that it was planned that Terumi and Noel were to fuse in order to create the Black Beast, but it ended in failure. She reveals that Noel wouldn't have wanted to become the heart of the man who destroyed her mind, took her family and everything away from her, even if she had died. However, she tells Ragna that everything went alright because Take-Mikazuchi had destroyed everything. Ragna asks Nu why Terumi wanted to become a Black Beast, but Nu tells Ragna to ask Terumi himself as she doesn't know.

Nu tells Ragna that her story is over and asks him if he had to come to destroy her, and goes back talking like her usual self. Nu then happily tells Ragna they should start killing each other right away and that Celica can join them, although Nu would kill her immediately. Nu then declares that she will "hug" Ragna again. Ragna declares that he did not come to kill Nu or destroy her, and points out the fact that she doesn't even die even if she "dies". Nu tells Ragna it is because of the Life Link that they both share, and points out that it is like a string of fate. Ragna tells her that they really need to end their negative relationship already. Nu tells Ragna that she wants to kill each other with Ragna forever, but Ragna tells her that it's over since she had asked Ragna to "save" her.

Nu denies saying anything like that, but Ragna tells her that the whole story that she had just told him was like asking him to save her. Nu then becomes angry and tells Ragna to drop the bullshit or she would kill him for real. Ragna taunts her, asking her to try if she can. Nu becomes more angry, while Ragna tells her to bring it on and that his method of saving is rough. Nu and Ragna then both fight. However Ragna easily defeats Nu even without the use of his Azure Grimoire, which makes Nu go into denial of how Ragna became stronger. Ragna tells Nu that it isn't that he is strong but that she is weak, while calling her the "strongest". Nu then falls unconscious, where Ragna catches her before she falls. Ragna points out that Nu's sleeping face looks similar to Noel, where Celica comments that Nu looks cute. Nu is then taken out from the Take-Mikazuchi by Ragna and Celica.

After Nu is taken out from the Take-Mikazuchi, Ragna asks Celica to heal her, where Hakumen asks him why he isn't killing her. Ragna tells Hakumen that he doesn't want to kill Nu, which makes Hakumen try to kill Nu himself, which Ragna and Celica both reject against. Suddenly, Izanami appears, which makes Ragna try to attack her, but because he doesn't actually attack her, Izanami asks if Ragna wants her. After Izanami talks quietly that "Brother is rejecting her again" in Saya's voice, she tells Ragna that he cannot save her forever, where Nu then suddenly attacks Ragna from the back. Nu tells Ragna to not say something sad as "saving her", then Ragna falls from his injury. After that, Nu's whereabouts became unknown.

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.

Despite being known to love Ragna very much, Nu shows anger against Ragna for the first time when he declares that he would "save" her.

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.

Nu also shares a Life Link with Ragna, which makes her become unkillable by normal means unless Ragna and herself were to be killed at the same time, be killed by Izayoi's Immortal Breaker, or be killed by Hakumen's Time Killer technique.

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?"
 * On the Japanese official website, 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's 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.
 * In the Epilogue of Continuum Shift, Hazama called Nu "Izanami no Tsurugi", yet during Chronophantasma, she is called "Izanagi no Tsurugi".
 * 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.
 * Nu's birthday is New Year's Eve, as well as being the last day of the year on the Gregorian calendar.