When spiritualist Himiko Se is hired to investigate a recent slew of murders whose victims were completely drained of blood, she does not expect to encounter a real vampire. However, Miyu Yamano is exactly that, as well as being a guardian between the dark realm of the Shinma and the human world. As creatures with godlike demonic power, Shinma terrorize innocent people, and one in particular has been masquerading as a member of the noble vampire race. As Himiko continues her investigation, she has trouble believing that Miyu is truly innocent, and fails to understand why a vampire would protect humans from Shinma.