Monster girls have an almost impossible time becoming pregnant. Only about .2% of the time having sex can one get pregnant. For this end a special school has been created. Here humans and monster girls can attend school together where daily sex is required and open sex is encouraged.

After his marriage to Hakua Taichi lives every day now in lovey dovey baby making sex with his wife. He runs into Ooko the student council president (quite literally). Ooko is strict and hard to approach. Because of this nobody has asked her to be their baby making partner. Although sad that she's alone she will not change her attitude or her duty to the school. Leaving her with little hope of finding a partner.

When Taichi calls her cute, instead of 'strong' or 'cool' like all the other students her heart begins to beat. Meanwhile Taichi thinks to himself that, since it's all right to marry many monster girls he should have lots of wives and make lots of children so he decides to show Ooko love and happiness.