Trying to find a hentai Tankoubon that starts starts as the story of a girl working at some kind of Brothel and ends with a guy accidentally walking in on his younger sister-in-law changing and they start an illicit relationship which his wife knows about and accepts. I've been looking for this for almost a year, but I just can't remember the name. if you have ANY clues at all as to what it might be, I would REALLY appreciate the info.