Mu-Hyang is the second Prince of Myung-Joo and the step-brother of Hong-Ryung.
He has long dark green hair and a calm, kind look on his face. It is hard to tell what he is thinking as nothing is revealed through his facial expressions.
He is a calm, gentle person who seems to care for his little half-brother, Hong-Ryung, and not care about being king. Although, he does submits to his mother and her plans reluctantly. Though, it is extremely hard to tell whose side he is actually on.
Mu-Hyang is the second prince of Myung-Joo since his biological father is supposedly the late King of Myung-Joo and his mother is the late king's concubine, Chui-Bi. However, though he was born before Hong-Ryung, he was not made crown prince by the late King of Myung-Joo for reasons yet unexplained. One possible explanation however, as was revealed later in the plot, is that Mu-Hyang is not really the son of the late King, but was born to a different father. Nonetheless, despite this knowledge, the late King loved Mu-Hyang as his own and acknowledged Mu-Hyang as his son, but stopped short of making him crown prince.
When his mother, Chui-Bi, plotted to assassinate Hong-Ryung, Mu-Hyang was enraged and threatened his mother to stop or he would never forgive her. Nonetheless, afterwards, he begged the Hong-Ryung, to spare his mother's life.
Additionally, although he said that had no interest in the throne, he agreed to stand in as king while Hong-Ryung was missing.
His step brother. Mu-Hyang cares for his step-brother. Mu-Hyang promised Ga-Bi to protect Hong-Ryung after Chui-Bi almost successfully assassinated Hong-Ryung.