The setting is Asakusa.
One day three 2nd year middle school students; Kazuki Yasaka, Tooi Kuji and Enta Jinai meet a mysterious kappa-like life form known as “Keppi”, forcibly have their shirikodama stolen and get transformed into kappa.
“If you want to return to your original form, connect in “that way” and bring the zombie shirikodama”.
Is what Keppi tells the trio. Can the boys connect and steal the zombi shirikodama?!
At the same time at the police station where Reo Niiboshi and Mabu Akutsu work something is about to happen.