Detective Hoshino visits the mansion of Miyako Rozmberk in order to investigate the murder of her former maid. She blames the murder on a man named Ukyo Kuronuma, whom Hoshino catches in the act of biting a young girl’s neck as she begs for her life. Ukyo was once known as Okita, a swordsman from Edo period who was turned into a vampire by Miyako. Hoshino soon finds himself turned into a vampire as well, and ends up in a battle with Ukyo for the right to spend eternity with the irresistible Miyako.