Harakami

Susumu sees a girl masturbating in an empty classroom at school. She asks him to watch her but embarrassed he runs away. When he arrives at home she's waiting for him. Her name is Koko and she claims to be a goddess. She asks to have sex with him immediately and not wanting to pass up an opportunity he does. She immediately announces her pregnancy and congratulates Susumu on being a new father!

Koko explains that Susumu is special and has a high chance of making girls pregnant, in addition each time he makes a girl pregnant his impregnation power will rise and it'll be easier for him to make girls pregnant.

Meanwhile two girls Meina and Kei beg Susumu to join their new club at school so they can have the minimum required 4 members and so he does. Just what sort of club is this?