Basically the mc is a receptionist who gets transferred to a parallel version of his own world where women and men's ideas of beauty are backwards, and there is a shortage of men to begin with. So ugly people are beautiful and vice versa. Except MC who is called average but is never treated like it.
About 70-80% of it is softcore porn. That's it, I've legitimately seen hentai with more plot than this. In volume 3 there's a loredump about how a japanese guy got isekaid to this originally, of course, he used to fuck all the time and he bares a ton of resemblances to our MC. Probably an ancestor. There's virtually nothing interesting done with the premise, it's just a typical "eeeeeeeeh????! You want sex with meeeeee??!" Mc fucking tons of easily impressed beautiful women who do all the work in the non-existant relationship. There is no story, just read hentai.