All roles are performed by adults. After enrolling at a school where joining a club is mandatory, an adult student with no particular interests meets Ms. Hatano. Her gentle smile leaves him smitten at first sight, so he joins the swim club she advises with ulterior motives. As its only new member, he begins spending every afternoon alone with her cleaning the pool. Soon he cannot take his eyes off her soaked T-shirt or the racing swimsuit digging tightly into her crotch.