Μ-No.12-

""I've arrived. Reborn as Kusanagi. The destroyer of all living creatures. I am death...""

μ-No.12-, commonly abbreviated as Mu-12 and known as both Kusanagi and the Sword of the Godslayer is a Boundary Interface Prime Field Device, Murakumo Unit, and the alter form of Noel Vermillion. Originally birthed in the 5th Hierarchical City of Ibukido, Mu was a depressed and murderous Prime Field that remained as a repressed part of Noel's soul. This part of her has disappeared with time, and her powers are used by Noel in times of need.

Mu first appeared as the final boss of BlazBlue: Continuum Shift, being unlocked once the true ending of story mode is completed.

Personality
"Although she appears calm and collected, she is actually quite lonely. Moreover, she is shy, and is bad at forming close personal relationships. She is good at fighting, but outside of that she is unskilled. Her cooking boasts the ability to kill people."

Continuum Shift
"The Successor of the Azure and the 12th Prime Field Device, as well as the true form of Noel Vermillion. The sublimation of the Murakumo Unit, the "Sword of the Godslayer Kusanagi" shown itself for the sake of destroying the "Master Unit Amaterasu"..."

Chrono Phantasma
"The Successor of the true Azure and the awakened form of Noel. The ultimate Boundary Interface Prime Field Device. She was the "Sword of the Godslayer Kusanagi," the only one able to destroy the Master Unit that exists in the Boundary, but with the help of Ragna, Noel was able to retain her self-identity. So, to save her best friend, she asks Rachel to teach her how to control this power."

Central Fiction
"The Successor of the Azure and the 12th Prime Field Device, as well as the true form of Noel Vermillion. She awoke in Kagutsuchi as the "enemy of the world," and was attacked by her friends one after the other. In order to discover the true meaning behind this phenomenon, she begins to act."

During the confrontation with Ragna, Mu was split from Noel’s soul and became her own separate entity, but maintained Noel’s memories and personality. Mu-12 was also absorbed into the Embryo, but was sent to a different world from the others. In this reality, she had murdered many people, including her friends. She discovered Makoto while still unaware of her circumstances and was attacked by her. She fought back and knocked her former friend down.

Inside the NOL branch of Kagutsuchi, she found Tsubaki, who turned her blade against the Godslayer and asked if it was fun to kill so many people and take their futures away from them. Tsubaki transformed into Izayoi, and the pair fought until a phenomenon intervention took Izayoi away. Mu began to despair over her circumstances, but resolved to find the Cauldron. Kagura blocked her way, his words making her lose control. She fell into a depression and stopped acting like Noel and more like the original Mu-12. Once she killed the illusion of Kagura, the cauldron opened itself up.

Inside the cauldron, Mu discovered Es guarding the Gate. The two fought briefly before Mu lost to Es, and was sent back to the original, real world. There, the real Hazama found her and managed to manipulate her into a robotic trance, whereupon he ordered her to kill the real Ragna. She complied, but Ragna freed her from her trance, and she was able to direct him out of the phenomenon event and back to his original reality. Mu attempted to follow but couldn’t, and asked Ragna to bring Noel to a cauldron so she could fuse with her again. Ragna fulfilled his promise and brought Noel to a cauldron, but Noel rejected Mu, forcing Mu to wait until her other half was able to accept her.

Mu was finally accepted by Noel later when the latter used the Azure Grimoire as a cauldron. With this, Mu finally reunited with the other half of her soul. Noel would later use Mu’s power to fully absorb Izanami and Saya into herself, and become the complete whole of Saya.