Haramaseya

Akito Terada is an ordinary salaryman, except that he has a special physical characteristic that made his injuries heal unusually quickly. His grandfather, a genetics researcher, conducts a thorough examination of Terada's body... blood, cells, and sperm, and finds that he not only healed quickly, but also had a gene that made him very fertile. Terada is traumatized by the thought that any woman would get pregnant if he had sex with her… Until a sperm bank learns of this and asks Terada to donate his sperm. Terada was suspicious of the request, which smelled so fishy, He accepts the request, but only under the absurd conditions that the recipient must be a woman under 30 years old and that the donation must be done via direct sexual intercourse. Later that day, such a request actually came in…

(Source: cmoa, translated)

Note: Includes “ Haramaseya 3.5”.