Kaname Okimura, a student of Prefectoral Umineko Shougyou High ("Umisho" for short), joined the school's swimming club in order to learn how to swim, but the club is filled with weirdos, let alone teach him swimming. Then, a sunny, happy-go-lucky girl named Amuro Ninagawa who was transferred from Okinawa joined the club. Her extraordinary underwater speed and unorthodox swimming su-ta-i-ru (plus her personal habit of nude swimming -- a powerful magnet to teenage boys) surprised every club member, especially Okimura, because she reminds him a mermaid-like creature he saw only once in his early childhood.

Umisho wins because green-hair wins. I got this on a whim and I have to say it's quite fun. The fanservice is interestingly, well, "clean." You'll understand what I mean.

By the way, the main male lead seriously looks like Kyon.