Blood Lad

Blood Lad is a manga series created by Yuuki Kodama. It is about a vampire who falls in love with a human girl.
Plot.
One day a high school girl wanders into the monster world and lands in the territory of a vampire. The vampire falls in love with her. But she is eaten by a carnivorous plant and turned into a ghost. The story is about him finding a way to make her human again.