またにてぃもんすたぁず！～純情な淫魔と清純な不純異性交遊！～

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 finally convincing Nora and Ooko to get along Taichi marries Nora and makes her his exclusive monster girl. Now that Taichi has 3 monster girl wives Maya, the succubus who works as a doctor for the school calls him into her office. She is concerned that Taichi has married the three most beautiful girls in school and taken them out of the school's impregnation project despite the difficulty in getting monster girls pregnant.

Taichi needs to prove himself that he can handle all three monster girls alone. It wouldn't hurt if he added one more girl to his harem to do so, would it?