The women of the Yarim family are filled with lust. Mom Mitsuko and second daughter Sayoko constantly bring different men to the house, while the head of the family is on permanent business trips, and everyone who comes to visit them can have fun with the girls of this family as much as they can. Mitsumi Kurumi, tries to resist such debauchery in the family, but can't resist her genes, and is constantly aroused, which negatively affects her studies. Because of this, it was decided to hire her a private tutor to raise her academic performance and improve her overall score. And on the first lesson in biology, while the tutor explained one of the options for breeding plants and animals by crossing, Mitsumi understands that he can no longer resist his gut, and asks the mentor to move from theory to practice, clearly showing the options for crossing people, since this is much more interesting.