Nachi Shinohara is a popular, easygoing high school student who gets along with everyone and enjoys a carefree social life. In the same class sits Yuuri Takizawa, a beautiful but solitary girl who spends her days reading novels alone, never interacting with classmates. After a chance incident where Nachi picks up a book she dropped, he becomes curious about her. He buys the same book, and they begin talking. Yuuri invites him to her home to recommend more books, and soon they start a secret relationship. Nachi insists on keeping their relationship hidden because he wants to monopolize her entirely, and Yuuri agrees.

The story follows their intimate and sometimes awkward romance as they navigate first love, jealousy, and physical desire. Nachi, who previously had casual relationships, now finds himself intensely focused on Yuuri. Yuuri, initially reserved and guarded, gradually opens up and reveals her own passionate side. Their secret bond deepens through stolen moments at school, visits to each other’s homes, and shared experiences like their first date and the cultural festival. Subplots include the return of Nachi’s ex-girlfriend Makoto, who causes brief tension, and the development of a secondary couple between Keigo Amami, a quiet coworker of Nachi, and Makoto. The narrative balances sweet domestic scenes with more charged, sensual encounters, portraying the couple’s emotional and physical growth over the course of their high school life.