The Pain in My Neck

Recently something's really been doing a number on Su-Min. No medical test can seem to tell what it is, though. After several unsuccessful checkups, Su-Min walks home to find…his next-door neighbor drinking the blood of a random stranger! Su-Min’s thoroughly creeped out, but he soon becomes interested when the vampire claims that he can suck all of Su-Min’s pain away. What could possibly go wrong? It’ll be worth it if a small pain in his neck will rid him of this mysterious ailment, right? Right? (Source: Lezhin US, edited)