Despite the title, there are no water sports in this doujinshi. Just one girl has her toilet malfunction and doesn’t manage to reach her neighbor's in time.

That neighbor (the protagonist), then invites her to get in and have a shower. Turns out, he got more than he bargained for, as heroine is a horny virgin who loses control once she’s left alone in a boy’s bathroom...
*All characters depicted in this work of fiction are adults, regardless of their visual representation or textual description, and are not based on any real person*