The women of the Yarima family are overflowing with lust. Mitsuko's mother and second daughter Sayoko constantly bring different men to the house while the head of the family is on constant business trips, and anyone who comes to visit them can have as much fun with the girls of this family as they can. Mitsumi Kurumi, trying to resist such debauchery in the family, but can not resist her genes, and is constantly horny, which negatively affects her studies. Because of this, it was decided to hire her a private tutor to raise her grades and improve her overall score. During her first biology class, while the tutor was explaining one of the options for breeding plants and animals by crossbreeding, Mitsumi realizes that she can no longer resist her gut, and asks the tutor to move from theory to practice, visually showing options for crossbreeding, as it is much more interesting.