This one ?? It's on chapter 1 . http://www.mangago.zone/read-manga/fuuzokugurui_desu_ga_toshishita_danshi_ni_kokuraremashita/
is this it ??? ヾ(❀╹◡╹)ﾉ~ http://www.mangago.zone/read-manga/fuuzokugurui_desu_ga_toshishita_danshi_ni_kokuraremashita/
I dunno if this might help, but I think it's kinda similar, I guess?
http://www.mangago.zone/read-manga/straight_kun_to_gesu/mi/e3927025a15fab2405f8e92c43e04625_chapter-1/
Or the second story of this manga?
http://www.mangago.zone/read-manga/24_jikan_eigyouchuu/tr/85059/page/
Yea it's the first one... I already found it the moment I asked this question.
The seme and the uke work at a book store. I think the uke is a manager. I think he has a sex addition or he just went to those stores a lot. The seme is a very stoic and almost like a robot. He is also younger than the uke.