In a world where vampire attacks are a serious problem, Isuzu Osaka works to hunt them down, and he decides to enlist the help of the vampire Baroque, a known vampire killer, to hunt the latest criminal, even if that means breaking Baroque out of jail, himself. Though it causes a lot of trouble, the two are eventually allowed to work as a team, exterminating vampires together. I think they're both interesting characters, though Baroque is drawn quite young, so maybe avoid if you're sensitive to "lolicon" type settings.
Boku no Noroi no Kyuuketsuki