With an absent father and having had a traumatic experience in pre-school, Himari Uehara has problems dealing with girls, and knows nothing about sexuality. He joins a boys-only high school, makes a good friend, and his now happy school life is marred only by the disconcerting changes in his body. His new friend, Gaku Asada, realizing Himari's ignorance, offers to teach Himari how to take care of his male physical needs...