Nice catch!
The club's called "Star Drop," so maybe there's an entire series of stories that follow the various prostitutes~ There's no doubt the adorable complaining kouhai is going to get his own happy ending ;P
Yeah! I read Kichiku, Encount again just to spend some time and at the end of chap.1 noticed the same too! But I think that Chihiro probably works as a prostitute and porn actor, because when he gets a phone call the other guy says that he stood a woman for a "meeting" xD But he also says that he's been 2 months without sex. I think the guy was happening for something similar as the character of Rinka from Leopard Hakusho, too much boring sex he was impotent xD crazy theories
Anyone notice that the business card that Chihiro has and the one that the Haruya has have the same design?
http://www.mangago.zone/read-manga/kichiku_encount/mf/c001/30/
http://www.mangago.zone/read-manga/junjou_bitch/bt/331892/Vol1_Ch1/9/