18+ Harem Kakumei

Haruo's father makes him crazy. He's a brilliant doctor, but he also has 4 wives. At the same time, none of whom are his mother (who died when he was young). Haruo is doing his best to get away from this insane home life and has just started college and has become reacquainted with a girl Moera that he used to have a crush on. They even start dating when life throws him a curve—his father has picked up a fifth wife, and it's Moera!!!

(Source: Animeraider)