It's been a long winter for humanity, which has been deposed from its throne after being defeated in the great war against vampires. A small city-state surrounded by a massive wall of light has become one of the human race's last strongholds, its leaders determined to reclaim control of the world they have lost. Within the oppressive city walls, however, young Momo fantasizes about coexisting peacefully with humanity's greatest foe. Fine, the vampire queen who once loved a human, has decided to flee the battlefield. The two are viewed as traitors by their own kind and have a fateful encounter during yet another savage battle. They embark on a journey in search of "Eden," a mythical utopian garden of peace.