In the kingdom of Kouka, Princess Yona lives a sheltered but peaceful life with her pacifist father, King II. Surrounded by attentive servants and protected by her bodyguard Hak, Yona's only difficulties in life are her unruly red hair and trying to convince her father to let her marry her cousin, Soo-wan. But on the night of her 16th birthday, Yona suddenly loses everything she holds dear and is forced to leave the castle. With no one left but Hak to defend her, Yona realizes that she must become strong if she is to survive. She embarks on a quest to find allies, and an ancient legend involving the Crimson Dragon King and his four Dragon Warriors may be her key to reclaiming her kingdom.