Responses
It reminds me of this http://www.mangago.me/read-manga/h_jigyoubu_eigyou_ni_ka/
It's the one I'm looking for! Even if i forgot the title, i still remembered the cover. Thank you so so much!!(⌒▽⌒)
The story was that there is a company or rather more specific, a department(ithink) who tries out their newly invented sex toys. It all began at the first chapters where there is a new recruit in their team and his first task was that. I just want to read it again but completely forgot the title! ╥﹏╥