A swimming contest is underway among the animals. Saru-kun, a boastful monkey, insists on competing despite being unable to swim. He jumps in and immediately begins to sink. The pool floor is unexpectedly covered in seaweed and coral, inhabited by a kappa, a water spirit. Saru-kun battles the kappa, taking its distinctive head-plate. The kappa agrees to let Saru-kun ride on his back in exchange for the plate's return. Saru-kun then swims effortlessly across the pool, appearing to swim on his own, and wins the race. But what will happen in the end?