In Asakusa, middle schoolers Kazuki Yasaka, Toi Kuji, and Enta Jinai run into Keppi, a creature who calls himself heir to the Kappa Kingdom. Keppi turns the three boys into kappa and sets them a task: defeat the zombies created by the Otter Empire and collect the Dishes of Hope, which grant a wish. The catch is the attack itself — the boys can only finish a zombie by linking together, and every time they do, one of their secrets spills out into the open.