Responses
This is a prostitute x murderer
https://www.mangago.zone/read-manga/boys_next_door/
Pawn's Revenge is also a prostitute × murderer lol. For something fluffier I'd recommend Killer Crush. Technically Boss, Bitch, Baby! also fits but it's not probably whay you're looking for. Oh there's Sleeping Dead, the vibe is quite angsty and I haven't finished it but you'll probably like it.
By any chance, is there a story about the romance between a civilian and a murderer? Pls reco me if u know one! ♪～(´ε｀ )