I remember reading this light novel. If you're into a savage MC like Leon here, this may be quite the treat. Best way to summarise, mob character with knowledge of this Otome game turns the world upside down as well as handling out fat L's to the main players.
Surprisingly enough there isn't much ecchi in this one. Well at least I don't remember there was (besides a scene or two).If the whole story is 'this looks like ecchi isekai trash and I'm 100% going to watch it' then you are correct.