Lambda-11

Nu-13 is a fragile and thin girl with pale skin, large, sunken red eyes, and gray hair. Most of her hair is worn in a very long ponytail, the end of which is attached to a sword-shaped metal object. On her face is a seithr regulator, which she wears as part of an eye patch. The symbol for a Prime Field Device is tattooed between her collarbones.

When in standby mode, Nu's clothing is a simple light blue one-piece jumpsuit with short leggings and long sleeves which wrap around her middle fingers in a way similar to bridal gloves. There are metal harnesses on her jumpsuit on the nape of her neck and under her breasts. Over this, she wears a white and blue cloak with various rings attached to it. These rings are adorned by red talismans with various symbols on them. The cloak has a huge collar, held upright by a metal piece imprinted with Nu's Prime Field Device symbol. Nu's battle gear is very similar to that of a mecha. Her face is covered by a visor with horn-like antennae and a single, glowing red eye. Over her jumpsuit, she wears a harness which is attached to a blue jewel and to her shoulder guards. These shoulder guards are blue and white, with a gray part on the nape of her neck, and there are two seithr regulators on the back of each shoulder. The shoulder guards are attached to her arm guards, which have small blades similar to her swords mounted on them. Her battle gear's most distinctive feature is the plate armor covering her legs. These armored leggings are mounted with blades that serve as weapons for her. Nu's hips, upper arms, and armored leggings have glowing green lights on them.

Nu is able to telekinetically control eight swords, which she uses as weapons in addition to the blades on her legs and forearms. These swords often float behind her in a pattern similar to wings. While in her battle gear, there is a small black marking in the shape of a sword on Nu's jumpsuit.

Lambda resembles Nu in nearly every way physically, except for her hair color, the tone of her skin, and her facial features. Lambda's hair is golden, similar to Noel's, her skin is a healthy light tan, and her eyes are wide open and bright.

Lambda's jumpsuit is identical to Nu's, but her cloak is very different. While it has the same collar as Nu's cloak, it has a golden piece of fabric resembling a necktie in place of the ring and talisman attached to Nu's collar. Unlike the one-piece cloak worn by Nu, Lambda's is split into 3 large folds, which are colored gold, black, and white. The two folds on the sides of her cloak are emblazoned with a large lambda letter and the text “No. 11” under it. Beneath that, in smaller text, is printed “MURAKUMO - UNIT ◄ idea DRIVE ► -2198-”.

Lambda's battle gear is completely identical to Nu's, except the color scheme is completely changed from shades of blue accented with green to black and purple accented with orange.

Opposite to her sister, Nu, Lambda is nearly always emotionless thanks to her memories being wiped by Kokonoe. She loyally follows Kokonoe's every order, and speaks in a cold monotone while using complex technical language. Nu's soul was initially injected into Lambda and sealed, but it has since disappeared. Because of Nu's soul, Lambda was able to develop some emotions, particularly towards Ragna. Unlike Nu's intense feelings towards the Grim Reaper, Lambda's is more subtle, and these feelings have persisted since her resurrection. Lambda felt so strongly for Ragna that she willingly defied Kokonoe's orders and sacrificed herself in order to save him.[5]

Time spent with Ragna, however, allowed Lambda to develop her own sense of identity. She displayed empathy and kindness towards both Ragna and an injured tartar, opting to spend to her own time trying to heal the insect instead of focusing on her primary directive to return to Kokonoe.

Before having her memories wiped, Lambda only knew suffering and was relentlessly experimented upon by scientists. She would cry out to be freed from the torture but she was unable to physically scream her terror. Thankfully, Lambda has no recollection of these events nor the trauma that was inflicted upon her.

Lambda is one of the first to have been implemented with an Idea Engine, which was created by Kokonoe. It allows its user to have capabilities similar to those found in Nox Nyctores type weapons. With the Idea Engine, Lambda has some immunity to Phenomenon Intervention, but this ability is unstable.

Lambda's Drive is Sword Summoner EX, which makes her summons sword projectiles at long ranges along with creating an additional projectile automatically after hitting an opponent. Lambda herself was also made stronger in close-range fighting than Nu. The two still share many moves, but the subtle differences mean the two of them perform very differently.

Because Lambda's armor is made out of titanium and other light metals, her defenses are inferior to both Nu and Mu-12. She does not wield a Lux Sanctus: Murakumo either, making her the weakest in both offensive and defensive capabilities out of the three units who inherited parts of The Origin's soul. Like Nu, however, she cannot be absorbed back into The Origin since she has come to form her own unique identity. Lambda's weakness in combat compared to her sisters can be best demonstrated by her being killed from only two hits by the Geminus Anguium: Ouroboros.