Kimijima Mio and Takarada Monami are sisters and their Mother is remarrying with another man. A man whole also has a son from a previous marriage: Hirata Tsukasa, a young and shy man who is about to enter college.
They all actually get along pretty well, as the 2 sisters find their new young Brother pretty cute.
Since the 2 families have moved to live together kind of suddenly they have space problems and so the Father suggest for Hirata to sleep with the 2 sisters in a room, just temporarily.
When the lights shut off, our good dude will discover these 2 busty sisters are on heat, and when life gives you lemons…