Ao Kurose is a shy and self-effacing first-year high school student who serves on the health committee, a post that leaves him unsupervised and alone in the infirmary after school. That solitude is shattered when he discovers the room is already occupied by Mio Haimiya, a second-year student whose appearance alone commands the entire school's fear. With a striking gray wolf-cut hairstyle, multiple glinting piercings, and a blunt, intimidating Kansai dialect, Haimiya has a reputation that makes classmates part ways when she walks down the hallway and causes even teachers to avoid her gaze. She is widely regarded as someone it would be suicidal to approach.

Against all expectation, however, Haimiya does not threaten or dismiss Kurose. Instead, she bluntly offers to help him with the cleaning. What begins as a bewildering, one-sided arrangement in the closed space of the infirmary slowly reveals a massive gap between her outer menace and her inner self. Haimiya is not actually a delinquent; she is deeply awkward, intensely shy about showing kindness, and utterly unskilled at expressing positive feelings. Every act of care she directs at Kurose comes out wrapped in brusque commands, fierce glares, and aggressive dialect, leaving him terrified and confused. Yet through small gestures—opening a window when she notices his hay fever, pressing an umbrella into his hands while insisting he not catch cold, sitting quietly beside him during a rainstorm—she demonstrates a gentle, almost childlike sincerity that he gradually learns to read past the surface.

The story unfolds as a tight duet between these two characters, with the high school setting providing a mundane backdrop for their increasingly entangled daily life. Kurose spends his days helping out in the infirmary, and Haimiya continues to be a constant presence there, using the health room as a refuge from a school that fears her. Their relationship develops through a series of episodic, slice-of-life events: walking to school together, being assigned to the same pool-cleaning duty, sheltering from rain under one umbrella, and dealing with the aftermath of Kurose overhearing classmates mock Haimiya behind her back. That last event becomes a notable turning point where Kurose, normally too timid to confront anyone, finds himself speaking up in her defense, and Haimiya, in turn, reveals a vulnerable side she has never shown anyone else.

As their bond deepens, Haimiya’s feelings evolve from simple interest into genuine romantic affection, yet she becomes increasingly frustrated by Kurose’s obliviousness to her hints. Meanwhile, Kurose’s own perception shifts from pure terror to curiosity, then to fondness, as he begins recognizing the lonely, earnest girl hidden beneath the fearsome facade. The narrative centers on the comedy and tension that arise when a person who communicates only through intimidation and a person who can barely read social cues try to close the distance between them, all while the rest of the school remains completely unaware that the scariest student on campus is desperately trying to be nice.