I got you
《ENNEAD》
https://www.mangago.me/read-manga/ennead/
100% what you're looking for.
《Profundis》
https://www.mangago.me/read-manga/profundis/
The plot and the smut are really good, but I think the r@pe is why a lot of people don't like it.
《Dark Fall》
https://www.mangago.me/read-manga/dark_fall/
You can't miss it. Also 100% what you want.
《Corrosive》
https://www.mangago.me/read-manga/corrosive/
Literally, everyone. And it's all r@pe.
《Love Remedy》
https://www.mangago.me/read-manga/love_remedy_1/
I didn't really like it because the plot is so stupid, but we are not looking for a decent plot here.
《Non Zero Sum》
https://www.mangago.me/read-manga/non_zero_sum/
It's traumatising.
《In the Castle: the Dragon's Erotic Education》
https://www.mangago.me/read-manga/in_the_castle_the_dragon_s_erotic_education/
I don't remember anything from the story, but I can confirm that it is what you're looking for.

Plss recommend me more stories like this, where the MC sleeps with almost everyone hahahahahah plsss(づ ̄ ³ ̄)づ