Mayuko Nise begins as a high school student fractured by relentless bullying and familial neglect, forging a psyche steeped in distrust and solitude. Thrust into a labyrinthine skyscraper realm, her trauma crystallizes into ruthless survival tactics—eliminating threats without remorse. A pivotal encounter with Yuri Honjo, who rescues her from despair, redirects her loyalty into an obsessive drive to shield her savior.

This devotion evolves into fiercely protective behavior, laced with jealousy when Yuri engages others, especially Rika Honjo, perceived as a rival for her attention. Subtle romantic undercurrents surface through blushing at Yuri’s touch and possessive gestures.

Visually, Mayuko sports blonde hair in a disheveled ponytail, a mole beneath her left eye, and a school uniform (white shirt, blue jacket, red tie, plaid skirt) later patched after damage. Her eyes shift from green in anime to brown in manga renditions.

A lethal knife specialist, she amasses a high kill count before enhancing her capabilities with a defective “angel” mask, boosting her physical prowess. Later, she dismantles the mask’s programming via defragmentation, unlocking heightened speed and strength to challenge entities like the Great Angel.

Her survival hinges on psychological fortitude and tactical acuity, though sporadic empathy leaves openings for manipulation. Gradually, she shifts from isolation to anchoring herself to Yuri alone, tempering violent impulses with protective resolve.

Interactions expose her complexity: clashes with allies like Kuon Shinzaki underscore enduring trust issues, while fragmented backstory glimpses a life of abandonment. Her surname, meaning “two rapids,” mirrors her turbulent existence.

Narrative milestones—declaring Yuri under her guard, harnessing augmented abilities in decisive fights, and chipping at emotional armor—trace her arc through the skyscraper’s horrors. The result is a survivor sculpted by loyalty, trauma, and the relentless will to endure.