Junior high students Kazuki, Toi, and Enta accidentally damage a kappa statue and are transformed into kappas themselves by Keppi, prince of the Kappa Kingdom. Keppi offers them a way to regain their human forms, but only if they help him hunt strange zombie kappas. Completing each mission requires the boys to confront secrets and feelings they would rather keep hidden, turning their supernatural predicament into a test of friendship, trust, and the connections they are afraid to lose.