Nightwalker : Midnight Detective

The lead character, Shido, is a smooth vampire who seems to flirt a lot and who tries to help people endangered by the Nightbreeds, demons capable of possessing bodies and stealing souls. His assistant, Yayoi sometimes seems more concentrated on her job than Shido, but he eventually pulls through. Riho, a young secretary who tries her best to help out without trying to get in the way, also has a secret crush on Shido.