The Empress Ki (2013)

Sung Nyang was born a girl but now pretends to be a boy to avoid becoming a palace maidservant. To get revenge on her enemies, she hides her true identity but gets caught up in a Yuan Dynasty conspiracy while watching over the Yuan crown prince To Gon, who was exiled to Koryo. Through a series of twists and turns, she saves To Gon, but her secret about being a woman is discovered, and she is forced to become a royal maidservant. To Gon was the rightful heir to the throne, which was stolen from him by his half-brother, who then exiled him to Koryo. To avoid being murdered, he plays dumb, but he has a fierce rage and sadness within him. He eventually returns to Yuan and becomes Emperor, and with the help of Sung Nyang, a royal maidservant, he becomes a dignified king and fights against those who are a threat to him.