Fami☆Resu ~A~ (Visual Novel)

Kosaku has come to Tokyo because of certain circumstances.
He is charmed by a cute girl who leads him to a family restaurant in Akihara.
Unlike a normal family restaurant, this one not only caters to satiate the desire to eat and drink, but also to the desire to copulate.
In fact, customers are allowed to have sex with the waitresses as much as they like.

[From DLsite english]