Furin Kazoku ~Goriyou wa Keikakuteki ni~

The main protagonist has just married. In the day of the wedding his wife's mother Michiko tells him "why don't you live here", and thus he decide to live with his wife's family which include her Mother, younger sister and elder sister. A few months have passed and the couple is feeling the pressure of marriage...Michiko and her other 2 daughters Kirara and Sekka decide to help out... a world of immorality is open before the protagonists eyes...