After accidentally breaking a statue of a kappa that serves as the guardian god of Asakusa, middle school students Kazuki, Toi, and Enta are transformed into kappas by Keppi, the prince of the Kappa Kingdom.

After accidentally breaking a statue of a kappa that serves as the guardian god of Asakusa, middle school students Kazuki, Toi, and Enta are transformed into kappas by Keppi, the prince of the Kappa Kingdom.