Amuro Ninagawa joins the swimming club at Umineko Shougyou High (“Umishou” for short). Her speed and unorthodox swimming style (plus her personal habit of nude swimming) surprises every club member.
In a particular school, there are girls who are secretly in training to become ninjas. Asuka, Katsuragi, Hibari, Ikaruga, and Yagyuu. This features their tumultuous school life as they pursue the path of the ninja!