Can't recall the artist or the title of a manga i saw here

Help me with this. What I remember is a bloke and 2 of his mates go to a brothel of some sort that normally only confines to kissing or touching. Thing is this guy is married and has never been to one but gave in to peer pressure, and lo and behold he meets his younger sister in law as a staff there, and they just go for it since the bloke already paid and the girl wants to be 'professional'. Quite certain the line "might as well" was used at this point. Anyway things get intense and the friends and their own partners get to hear the moans through walls and stuff.
Just can't get myself to manually browse through the thousands of items here so i'm hoping someone here knows what it is.