Sarah, a maid from the Kingdom of Saleil, is ordered by the king to marry the king's brother from the enemy country of Ferrier as a shadow warrior of the princess. Everything was supposed to be for the sake of the princess to whom she owes a debt...but the princess steals her lover, and even her lover ends up opening up to her! ? Sarah was betrayed by the people she trusted, and she was left in the depths of despair...she never let herself fall. She said goodbye to her beloved princess. She said goodbye to her lover who she loved so much. “I will definitely be happy in Ferrier!” Sarah decides. However, her important marriage partner is...her brother is a recluse, hates people, and always wears a mask! ?