Ajin possess beastly characteristics and are obligated to serve men in the military and women in brothels in this realm. Those with gifted prowess are drafted into the imperial palace as beast servants, serving as prized symbols and protection for their royal superiors and subject to their whims. Sogetsu, Rangetsu's twin brother, was taken from her and bequeathed to Prince Tenyou as a beast servant where he was enmeshed in lethal royal scheming. Bereft of any hope in a world overflowing with bitterness, Rangetsu must masquerade as a man to infiltrate the palace and avenge her brother. However, Prince Tenyou is not the person Rangetsu was anticipating, and the political machinations within the palace are enigmatic and pervasive. Is there any possibility for Rangetsu to procure justice for her brother or will she be yet another Ajin fatality in the royal power struggle?