Aiko Mimura is a woman reborn from a male soldier in a past life. She rises to become the military leader of a new crusade, successfully uniting the world under her command and abolishing all organized religion. Haunted by memories from her previous existence, she is driven to travel backward in time. This journey aims to resolve unresolved mysteries of her past and confront forces threatening humanity's future.

Her quest entangles her in a pivotal battle spanning timelines, positioning her actions as critical to preventing catastrophe. She navigates themes of identity transformation, the psychological weight of reincarnation, and the burden of leadership in a conflict merging personal history with the world's fate.

Framed as a warrior, her strategic prowess in uniting fractured societies is juxtaposed with her internal struggles. Her time travel serves both to alter historical events and to reconcile her dual identities and memories.

Her background includes enrollment in an educational institution, depicted in a school uniform. She possesses brown hair, grey eyes (alternatively noted as green), and a teenage presentation.