The imperial palace is a dangerous place, where Ajin boys with special abilities are conscripted as beast-servants for their royal masters. Rangetsu's twin brother Sogetsu was taken from her and fell victim to bloody dynastic intrigues. Now, in a world of bitterness, Rangetsu must disguise herself as a man to avenge her brother and find a way into the palace. But when she suspects Prince Kougai of wanting to harm Prince Tenyou, she confronts him and becomes the prize in a wager between royal brothers. Will she be able to survive and claim her vengeance?