An ordinary college student named Ichiro Suzuki. He's good-looking, but timid by nature and completely inexperienced—a total virgin. One day, while exploring his house's storage room, he stumbles upon a mysterious book. The book claims that by chanting a certain incantation, one can possess another person's body. Skeptical but curious, Ichiro recites the spell, attempting to possess his own sister. To his astonishment, it works—his sister's consciousness enters his body, and the story begins from there.