Mu-12

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.

Noel is a petite girl with green eyes and blonde hair that falls to her upper back.

Noel wears her NOL uniform, which consists of a blue beret with a metal plate that she ties her hair into and a sleeveless blouse that reaches down over her thighs, and bares her shoulders and upper back in a V-shape. The sides of the blouse are blue while the front and back are white, and there is black lining around the seams. Two diamond-shaped silver pieces hang on the bottom of the blouse. She also wears a detached white collar with a red tie, and blue, detached sleeves that are a little longer over the shoulder, with black cuffs that hang over her hands. Yellow trim lines the sleeves' upper and lower hems, and they are held in place by a silver metal armband pushed up to her upper arm. Each armband has clipped to a ring on it, a red ribbon with a triangular metal tip. She wears white gloves with gold on the back, black, thigh-high socks, and blue, tucked-in, heeled boots with white lining. The boots have gold trimmings, a yellow cross on the anterior, and a silver metal tip on the toes.

After abandoning the NOL, Noel donned a new outfit. She let her hair down and now wears two blue clips in her hair. She wears a sleeveless, collared, white undershirt zipped at the back, and a short, red tie. The undershirt ends over her stomach, baring a bit of her skin. It also dips low at her back, mimicking the shape of her NOL uniform's shirt. Over the undershirt, she wears a short blue mantle with yellow lining. Red ribbons with triangular steel tips hang from the collar over her shoulders, pinned to the cloak with straps along the outside of her arms. She wears a thick black belt with a golden buckle and silver accents over a pleated, blue mini-skirt with a yellow hem. She holds her guns, Bolverk, in criss-crossed red holsters strapped behind her hips. She wears the same white gloves, blue, thigh-high socks, and style of heeled boots as in her NOL outfit, but the boots lack the cross motif and bear a large golden zipper in the front.

over her emotions. She initially had great difficulty with socialising with other people, only being able to communicate because of Bolverk's ability to suppress emotions. In time, she eventually learned to interact with others, being polite, helpful, yet reserved. She is extremely close to Tsubaki Yayoi and Makoto Nanaya, and tries to get along with Jin Kisaragi despite the cruel way he treats her. She loves her adopted parents deeply, joining the NOL to save their name and often worrying about how they are.

She struggles with her identity as an artificial human, at one point calling herself a doll. These darker emotions caused her to hate the world, but they have since been quelled. As her soul is comprised of many identities, she focuses on the identity of Noel.

Because of how shy she is, Noel shops online and attempts to hide away from others. She can become easily flustered at the slightest of remarks, but does have nerve to fight forward and resolve to do what she believes is right. The former Lieutenant regularly writes poems, although she never shows them to anyone out of sheer embarrassment. Noel also has a weakness for things she deems cute or fluffy, such as Lao Jiu or Makoto's tail.

In addition, Noel is extremely sensitive to comments made about her small chest size. This often causes her to further withdraw into herself, although on occasion when others have mistaken her for a boy or a man because of her chest size, she can become angry to the point that she immediately attacks the offender with little warning.

Being Noel Vermillion's original form, Mu is physically identical to her.

When out of combat, Mu wears a cloak very similar to Nu's, but with a large blue jewel and harness attached to a small metal collar in place of Nu's much larger collar. Her jumpsuit is white, has slightly larger gloves, exposes her lower torso, and lacks pants, which she replaces with long white leggings. Her jumpsuit also has glowing blue jewels set in golden frames on her hips, which are also present on top of her leggings. The metal piece over her crotch is similarly golden. In place of Nu's seithr regulator, Mu wears a metal headpiece with her variant of the Prime Field Device symbol engraved into it and stiff, horn-like antennae, an article of clothing which she continues wearing in combat.

Mu's battle gear is similar to a mecha, just like her “sisters”, but with several key differences. She lacks a bodysuit, instead wearing a small blue, gold, and black garment which only covers the sides of her torso, her hips, and her crotch, exposing her back and front. Her gear has enormous blue and white shoulderpads with seithr regulators built into them, as well as a third, smaller regulator built into a gray metal object on the back of her neck. Under the shoulderpads, she wears a collar similar to that of a dress shirt, with a short red necktie. She has long blue gloves with golden metal guards on the hands, and metal mounts on her forearms for her blades, identical to Nu's and Lambda's. Her bladed leg armor is also identical to theirs.

Deep down, Noel has hidden feelings about herself which manifested into "Mu". This dark side that inhabits her soul only desires the absolute annihilation of the world and the Amaterasu Unit. Anyone who stands in her way is a threat that she will coldly execute without remorse or hesitation. In some moments, there was a glimpse at insanity as she manically laughed while indulging in her power.[4]

Underneath the mechanical coldness or moments of madness, Mu is lonely and feels isolated from the world. Her hatred for the world is only matched by her hatred for herself. Mu only considers herself a doll - something less than human. These feelings and the personality of Mu has disappeared and she has come to be an accepted side of Noel. Mu now has Noel's personality and uses her name. Official descriptions of Mu's personality are identical to Noel's to reflect this.

Using the fully awakened power of the Godslayer, Mu is one of the most powerful entities to have ever existed. As the perfect fusion of a portion of Azure with a Boundary Interface Prime Field Device, Mu boasts power stronger than that of the Black Beast. She can freely enter the Boundary and is capable of fighting off present-time Hakumen, then both Jin and Ragna the Bloodedge at the same time. Part of her combat power lies in the intricate usage of her Nox Nyctores - Lux Sanctus: Murakumo. By using Murakumo, Mu has the power to overwhelm opponents with its myriad of blades.

In gameplay, Mu has the Drive Steins Gunner. When pressed, a small device will be launched which shoots a thin projectile at the opponent after a brief charge time; holding down the button will delay the shot, but in turn, make the beam thicker and deal multiple hits. Most of Mu's moves keep her opponent at bay, stopping them in their tracks, although she can boast good close-range pressure and can use Origin to get out of opponent's pressure. Mu uses these Steins in lore as well, with their power being able to easily pierce people's bodies.

Mu's only weakness is her own doubts as Noel. As she is Noel herself, she also has the ability to wield the Arcus Diabolus: Bolverk and phase through enemy attacks. She is the ultimate Observer who can make anything reality by just recognizing it as such. No one has stood on an even ground with Mu without having sustained life-threatening injuries - Ragna himself was shot by one of her Steins and lost his left arm to save Noel's soul from her transformation into the original Mu.[5] Even a victory against Mu means having to make large sacrifices.