Genre: Comedy, School, Sport

Within the Kanagawa prefecture lies the seaside city of Umineko. There, Okiura Kaname, 2nd year high school student, attends Umineko Shougyou High School, or Umisho for short. He is also the manager of the Umisho's swim team though he himself doesn't know how to swim. In fact, he is afraid of the water stemming from an incident which occurred some years ago. While he was at the beach, he had nearly drowned when a 'mermaid' pulled him under the water. One day, a floating house arrives at the shores of Umisho bearing two persons. One of these is a cheerful, if a trifle odd, girl named Ninagawa Amuro, a transfer student to Umisho. Her incredible swimming speed makes her an instant hit with the swimming club.