Rei Amagiri, a 15-year-old magical girl representing Tokyo, is charged with combating magatsuhi—malevolent entities spawned from worldly impurities. Her arc traces a descent into darkness and arduous redemption, defined by internal conflict and unhealed trauma. Initially driven by unwavering courage and duty, she fiercely protected civilians from magatsuhi incursions. A pivotal mission failure, however, resulted in civilian deaths, among them an elderly man whose granddaughter witnessed the tragedy. Consumed by guilt, Rei’s fractured psyche left her susceptible to manipulation by Libby, a magatsuhi-possessed ally who lured her into becoming a "magatsuki": a fallen magical girl fused with corrosive darkness.

Corrupted Rei embraced ruthlessness, clashing violently with former allies. Her powers escalated to absorb ambient energy, amplifying her combat dominance. She wielded a lance-shaped Sealing Tool resembling Tokyo Tower, mirroring her bond with the metropolis. Enhanced speed and strength rendered her nearly invincible, yet flickers of her former self emerged in brief, poetic appreciations of beauty—jarring contrasts to her brutality.

A confrontation with Mebuki Konoe of Kyoto and allied forces proved decisive. Severed from external energy sources, Rei was defeated and purified, reclaiming her sanity. Though reinstated as a protector, she grapples with profound remorse. Shards of her dark persona linger, erupting as erratic aggression or mood shifts—haunting reminders of unresolved turmoil.

Her past reflects a tragic cycle of duty and inherited trauma. Public scorn and guilt over her failure corroded her resolve, enabling external forces to weaponize her despair. Post-redemption, her story orbits the tension between atonement and the ever-present specter of relapse.

Physically, Rei stands 158 cm with black hair, piercing red eyes, and a stoic demeanor. Born June 6 under Gemini, these traits anchor her among magical girls symbolizing Japan’s prefectures.