The story revolves around Yona, the sole princess of the Kingdom of Kouka. Like princesses in general, she lives a happy life in the castle filled with luxury with her father, King Il; her servant, Son Hak; and her cousin and love interest, Soo-won. However, everything changed on the night of her sixteenth birthday. Intending to tell her father that she cannot forget her love for Soo-won, she visits his room, only to witness her father killed by Soo-won, who reveals that he…