Well it's good to see that a year after I wrote my review somebody else saw that the series was great (after my review of course). I just checked the DVD of "Midnight Detective" not knowing what to expect. I've never seen the series or heard the Anime, but I was completely surprised and impressed by this Anime.
The series combines "Interview With The Vampire", "Blade" and "Vampire Hunter" all in one.
The series is about a detective named Shido who is part vampire and part human. He solves cases involving what's none as the "Night Breed". The Night breed are vampires with major exceptions. The Night Breed can occupy the bodies of their victims and use and abuse them till they die. When their victims die, the Night Breed, inhibit another unsuspecting victim, by eating biting them or sucking their blood like a vampire.
Yayoi is part of the Nos, which is the Japanese equivalent of the FBI.
Shido and Yayoi work together to try to stop the breed but meet tough foes like Cain.
Cain is the head vampire, who like Lestat in Interview With The Vampire is the one that gives Shido , "Eternal Life" by being a vampire.
Now I actually was fortunate enough to see the 2nd DVD for "Midnight Detective" episodes 7-12 which is actually the end of the series. (The rest of the series) and I am glad too because it's out of print. Ironically I found it at Blockbuster which is virtually sucky in these areas.
The 2nd DVD and rest of the series does answer more questions about Shido. You will definitely want to check out the rest of the series if for whatever reason you can find the first six episodes.