In 12th-century Japan, the swordsman Kurou flees from ghastly pursuers into a deep forest alongside his servant Benkei. In search of shelter, the pair stumble upon the secluded dwelling of the mysterious and beautiful Kuromitsu. Although they are welcomed warmly, the men are cautioned never to enter Kuromitsu's room. However, driven by innate curiosity and perhaps a doomed love, Kurou peeks through the slightly open door, only to discover Kuromitsu feasting on the blood of fallen men. He soon learns that Kuromitsu is an immortal vampire and dedicates himself to her—even transforming into a vampire himself to spend eternity with her. But the cryptic organization known as the Red Army has enlisted Benkei's help, leading him to betray Kurou and sever his head. Awakening centuries later in an apocalyptic modern-day Japan, Kurou sets out to reunite with his lover and exact revenge on the Red Army.