Natsuo Fujii, a high school student, lost his virginity to a girl he met just a few hours earlier in the movie Domestic Girlfriend one day. The young woman, whose name was Rui Tachibana, pushed Natsuo into bed even though she had no true affections for him and only wanted to gain some experience. But following the incident, he feels bad since he feels cheated on by his crush, instructor Hina Tachibana. It turns out that the two women are sisters as well! The five now reside together in a new home as a result of the arranged union between Natsuo's father and the mothers of the two sisters. How will the three young people's relationship progress going forward...?
