Kamigaya Kai, a high school girl, frequently receives confessions from others. To prevent further approaches, she proposes an unusual condition to her suitors - "I will confess my love to you if you let me stab you to death." She finds her life dull, with monotonous parents, classmates, and media.
Unexpectedly, Kuwashima Kusabi, a seemingly ordinary girl, injects vibrancy into Kamigaya Kai's uninteresting world. At first, Kamigaya dismisses her as just another confession, but a surprise awaits her when Kuwashima returns home to retrieve a more durable knife.
