Hero killer (not many chapters have came out but she is pretty merciless from the look of it)....
The only story that I could think of is unholy blood but you might have already read that.
Yes and i like it
How about this one? I really like it: https://www.mangago.me/read-manga/crimson_karma/
I'm already reading this and i also like it
I'm searching for an action Webtoon with a female lead i prefer when she is merciless