Ajin boys who show signs of special abilities are conscripted to serve in the imperial palace as beast-servants—status symbols and shields for their royal masters, to be kept or discarded on a whim. When they were children, Rangetsu’s twin brother Sogetsu was ripped from her arms and sent to the palace to attend Prince Tenyou as a beast-servant, where he quickly fell victim to bloody dynastic intrigues. Now in a world that promises only bitterness, Rangetsu’s one hope at avenging her brother is to disguise herself as a man and find a way into the palace!

As the battle against Rohan wears on, Rangetsu must rely on sheer grit to survive until finally her desperation unleashes a new power within her. She strikes down foe after foe, lest she lose the country, the friends, and the man she loves. Will she ever see Prince Tenyou again?