Princess Yona is the only child of the ruler of Kouka Kingdom, Emperor IL. One week before her 16th birthday, Yona is determined to impress her older cousin, Soo-won, and make it clear to her father that she wants to be with him. However, IL does not approve, as he will ultimately be the one deciding who his successor will be. When Yona attempts to confess to Soo-won, he interrupts her. Yona's birthday party is held in the castle and Soo-won gives her a hairpin for a gift, and tells Yona (contrary to her beliefs) that her hair is like the colour of the sky at dawn. Yona decides to try to convince her father again, but upon arriving in his room, sees Soo-won stab her father.