The stage is Asakusa. Second-year junior high school students Yasaki Kazuki, Kuji Yuu, and Jinnai Enta encounter a mysterious kappa-like life form "Keppi" one day, and their kirigama are forcibly taken away and they become kappas. "If you want to return to your original state, you can connect with each other through 'a certain method' and take the kirigama of the zombies." Keppi tells the three of them. Can the boys connect with each other and take the kirigama of the zombies? ! At the same time, something seems to have happened at the police station where Reo Shinboshi and Shinbu Akutsu are on duty.