The vampire is certainly a popular figure in anime, spawing films from Vampire Hunter D to series like Vampire Princess Miyu. Though the ideas and stories of NightWalker are not exactly original, the anime OAV (direct to video) series is rather cute and entertaining.
Private eye Shiro's secret is that he's actually a vampire, but one who has taken on the task of defeating the creatures of darkness in a futile quest to redeem the fall that transformed him to a vampire--viewers may find this similar to television's Forever Knight. Created by a powerful vampire bearing the biblically-suggestive name Kain, Shiro also bears a sprinkling of Anne Rice.
Shiro's partner, paranormal cop Yayoi, offers her own blood to sustain him as the two must defeat the "night breeds" in a series of six related yet distinct episodes. His "kawai" schoolgirl secretary Riho--though not immediately in on the secret--also finds herself caught up in the struggles between good and evil.
The series as a whole bears out a plotline of darkness verses light, with humans subverted by demonic forces to fall from grace and both Shiro and breeds wishing only for a life again in the light. The characters are what really drive the story, though; their interactions through a couple of episodes should draw in most viewers as they come to care about Shiro, Riho, Yayoi, and Shiro's impish, voice of his conscience sidekick Guni.
The English voiceovers are passable, but most anime purists will prefer the Japanese with subtitles option. The special features aren't incredibly detailed but do include scripts, an art gallery, character info, and production data.
I found that the cliches presented did not detract from the overall stories and came to rather enjoy the series as a whole. If you're looking for something different in vampire anime, give NightWalker a try.