The animals are having a swimming contest. The strutting Saru-kun, a monkey, can't bring himself to admit that he cannot swim, and puts himself forward as a contestant. He dives right in, but immediately starts to sink. For some reason the bottom of the pool is littered with seaweed and coral, and a kappa, a type of water imp, also lives down there. Saru-kun fights with the kappa, and manages to seize the saucer off its head. The kappa agrees to let Saru-kun ride on his back while he swims, in exchange for the return of his saucer. Saru-kun then cruises right through the pool, looking for all the world like he is swimming under his own power, and wins the race successfully. But what happens in the end?
