Shimura Mami, a high school student in a futuristic metropolis, serves as the youngest operative in a clandestine crime-fighting unit. Her cheerful demeanor and infectious energy contrast with a tendency for mishaps that inadvertently disrupt missions. This recurring clumsiness prompted her replacement as pilot of the green combat mecha Gion by Annie—an android duplicate designed for tactical precision. While Annie now spearheads field operations, Mami monitors missions remotely, grappling with doubts about her relevance to the team. Standing 1.59 meters tall with dark green hair, brown eyes, blood type B, and a January 4 birthday, she channels her restless vitality into non-combat roles, resisting stagnation with relentless initiative despite her unresolved role within the group.