Kamigaya Kai, a high school student, regularly receives confessions from others. She sets an unusual condition: 'If you allow me to stab you, I'll accept your love.' This tactic keeps people at bay as she navigates her mundane life filled with uninteresting parents, classmates, and media. However, Kuwashima Kusabi, an apparently ordinary girl, injects brightness into Kai's 'boring' world. Initially mistaken as the fifth confession that repelled someone, Kusabi surprises Kai by returning home to retrieve a more robust knife instead.