Crépuscule

Orphaned Lark Alfen is taken to his new home by distant relatives. It's been said that his late mother was a vampire, so everyone is scared of him and doesn't want him around. He gets bullied a lot until, one day, he meets a black-haired boy named Setz who has red eyes like him. They become friends. But as a rumor spreads that Lark is also a vampire, his guardians decide to send him back to the orphanage. When Lark hears about their plans, he decides to run away, and Setz invites him to his home... in the world of real vampires.

Original Webtoon

Note:
Crepuscule was republished since it became popular enough that Naver chose to turn it into a professional work. The author and artist subsequently changed their professional names. This version was discontinued.