Condemned prisoner Leon continues his journey through the ruins of Tokyo in search of TORATSUGUMI, a mysterious weapon from ages past. Though mutated monsters lurk around every corner, Leon never thinks twice about abandoning his mission; it is his only hope of seeing his wife and child again. Fortunately for Leon, not everyone in Old Japan is out to kill him. He now has two unlikely allies in the form of Tsugumi, a bird-legged girl with inhuman strength, and Doudou, a fellow prisoner and one-time underground boxer. Leon will need all the help he can get, as his search for clues about the ancient weapon soon brings him face to face with creatures out of nightmare.