Hidomi Hibajiri, a discontented girl perpetually clad in headphones, leads a routine life centered around school, her mother's cafe, and music. However, her mundane existence is disrupted when a guitar-wielding woman collides with her. Subsequently, a robot invasion involving a classmate and the enigmatic woman thrusts Hidomi into a whirlwind of chaos. As a horn sprouts from her forehead, mysteries unravel, including the origin of these robots, the significance of a vespa-riding woman, and the peculiar growth on her own head. Hidomi's world, once shielded by music, now demands her active engagement.