TUTU

One of them is a white haired boy who fights some creatures that come from the ocean. his skin turns black after each fight and its known that he will die young because of that. he is some kind of special person, and others from his line did the same duty.

the other guy is a black haired boy that gets curious about him and then they fall in love (?). at some point the black haired guy gets kidnapped i think, and sees other white haired people.

MC was a human working for some supernatural agency, investigating crime (?) and demon contracts. I think he was investigating a woman's death (later the found out she made a contract with three demons), and this ML starts showing up. He has long blonde hair and orangeish eyes (i think).

He and MC actually met when MC was a young boy, and made a contract for MC's soul. But MC has been escaping him ever since (he looked like a girl before).

I think the ML turns out to be THE devil himself or smth, and his name was Raven?