Gokudou-san Series

Sachi is the physician of Amamiya clinic. One day, suddenly his yakuza childhood friend Kengo told him to raise Mushi, whose birth was kept secret. Thereupon, for Mushi’s sake, he pretends to be Kengo’s lover and lives with him?! He hates Kengo, who’s a yakuza, but… As they are taking a bath and going to amusement park together like a real family, the bond gets strengthened… Source: MU