Empress Huan is arranged marriage to the current Emperor of Yuan dynasty, yet the emperor loves her so much that he refuse to get concubines just to have his devotion to her. But as a rule of being an Emperor, he needs an heir to continue the lineage, which is you the chosen one and currently carrying his child. Just a month before giving birth, the empress called out for you and that's when you discovered her real identity, she is in fact a man.