Shido Tatsuhiko is not only a private eye, he is also a vampire with no real memory of his past. He is joined by Yayoi Matsunaga, a female goverment agent, Riho Yamazaki,an orphaned teenage girl working as his girl friday and Guni, a little green imp. Together with Shido they must face and defeat demonic creatures known as Nightbreed. Meanwhile, Cain, the vampire who sired Shido is seeking him out.