Looking for a manga where the main character enrolls in a "sex art"-class where the students have sex in pars of two. He gets pared with the sister of a famous former member of the class and they work towards a national competition. There is also a blonde rival of the famous sister that is the current nr 1. Does any of this sound familiar to someone?
Nvm, found it: "Kisaragi Gunma's "It's a Straight Line Once You Fall in Love""