Ok first of all i wanted to say is that the animation is mind blowing and yes, thats a huge statement but i damn well know what i'm talking about and when you take a look at one of the episodes, you'll get the idea too. Besides the beautiful animation, there is the element of blood which is in ample quantity, in comparison to Hellsing and Berserk animes. Also as a plus point its about a vampire in the post-apocalyptic era.
Right now its on 09th episode with a total of 12 episodes. Yes short and thats also the only negative point in the series. Too fast paced.
Story
The series begins in 12th century Japan and centers on Kuro, who meets a beautiful and mysterious woman named Kuromitsu while on the run from his elder brother, the founder of the Kamakura, who seeks Kuro's life. He soon falls in love with her, but then finds that he shares her fate and is now unable to die. In the far future, having lived for hundreds of years, but with his memories and Kuromitsu gone, he attempts to look for answers and find what has been lost. (Taken from Wiki)