Takuya's father died in an accident while conducting research. Concerned for his young stepmother, Ayumi, Takuya follows her to Ken point. Observing her and her best friend, Mitsuki, from behind a rock, he witnesses a sudden flash of light that transforms into an unearthly beautiful woman. The mysterious woman slips a ring onto his finger, and Takuya's journey into a parallel world begins. This ring serves as the key connecting Takuya to his various realities.