http://www.mangago.zone/read-manga/the_hero_who_seeks_revenge_shall_exterminate_with_darkness/ - I just noticed that the cover could fool you to think that a girl is involved but nah, he hates her to the bones. They should change the cover lol.
Thank you so much!
Thanks a lot ♡
http://www.mangago.zone/read-manga/litchi_hikari_club/
http://www.mangago.zone/read-manga/museum/
http://www.mangago.zone/read-manga/killing_morph/
http://www.mangago.zone/read-manga/offal_island/
I'm not sure if they're what you looking for but give them a try also Junji ito's some stories will match your request too like souichi's diary of delights. And http://www.mangago.zone/read-manga/aku_no_kyouten/ has a kind of smut scenes and slight romance but it'll do too.
A story with evil op mc. No harem, no ecchi, no romance, no cliche. An mc with pure evil intentions or someone who just kills for fun. Nothing heroic. I hope I can find one with good drawings. I'm tired of everyone just recommending death note. Thank you.