That Prince Is A Girl: The Vicious King's Captive Slave Mate

In the kingdom of Navia, a girl's birth is a curse. When Prince Garret and his wife Pandora learn their second child is a daughter, they hide her identity and raise her as a boy named Emeriel, swearing the palace healer and two others to secrecy. Twenty-one years later, Emeriel lives as a prince, guarded by his sister Aekeira and haunted by the attention his delicate looks draw.

But the tyrant King Orestus, who adopted the siblings after their parents died, rules Navia with cruelty, and Aekeira is not safe from the men who see her as a commodity. When Emeriel finds the minister of human affairs, Lord Murphy, forcing himself on his sister, he draws his sword to defend her, risking the secret that keeps him alive.

In a land where females are bought and sold, how long can a prince who is really a girl keep his secret?