Hayato hides the secret that he can't swim. He avoids school swimming tournaments. But, this time can't escape from swimming practice and is forced to participate.

Hayato, a boy in the 6th grade, hides the secret that he can't swim. Every summer, he pretends to be sick, so he could avoid school swimming tournaments. But, as it is the last year in the elementary school, he can't escape from swimming practice and is forced to participate.