Shiki is a classic vampire story with a few twists. The story takes place in a remote mountain village. A group of vampires moves in and starts feeding on and changing the villagers into more vampires. That's fairly classic vampire stuff.
Vampires are not portrayed as being inherently evil. They kill in order to feed, nothing more. However, the vampires also retain the personalities they had when they were alive. So a nasty person may actually enjoy the killing. An idiot is still an idiot. A good person may refuse to kill, effectively starving themselves. Very few of the characters that class.
For a vampire story, it is surprisingly bloodless, at least until the remaining humans start fighting back. Then it gets very, very messy. In fact, I found the last third of the series the most disturbing of all. The ruthless, almost casual, violence of the remaining villagers, easily surpasses anything the vampires committed.
The final twist is that leader of the vampires is a young girl who was killed hundreds of years ago. She's done some terrible things in that time and it weights heavily on her mind. Essentially, she is a child struggling to understand the morality of being a vampire. Intelligent vampire pathos is not a common approach to the genre.
In short this is a thinking man's vampire story.