kohaku's activites

I'm trying to find a manhwa that isn't in my bookmark anymore, but the character lead is some sort of demonic entity and it is in a female body. The character has short hair and red eyes, from what I remember. The character is evil, and kills everyone that comes in contact with it or some sort through some point. I remember one panel where character kills the whole town and the noble together by trapping them in the palace?

Isekai, the usual transmigration, reincarnation, time travel etc. except, you know, it's gay