Sakurako, a female college student, is a "little devil" who seduces her friends' boyfriends one after another. Plagued by a stalker, she asks Teruyama—the head of a detective agency she happened to meet—to investigate the matter. However, when Sakurako prepares to give up because she cannot afford the high fees, Teruyama makes her an offer: he will investigate the stalker for free if she agrees to take on a different job—an infidelity investigation...