He hails from a distinguished clan. While his lineage is notable, he himself is not. Cast out of his home, Ryosonuke survives as a kind of tradesman. After his sempai gives him a vampire doll, his split blood awakens it; following his sempai's death, he also comes into possession of a meat-eating girl. These two girls assist Ryosonuke in controlling the monster lurking within his blood, as various individuals pursue him for different reasons.