Princess Yona lives an ideal life as the only princess of her kingdom. Doted on by her father, the king, and protected by her faithful guard Hak, she cherishes the time spent with the man she loves, Su-won. But everything changes on her 16th birthday when tragedy strikes her family!

Yona and her friends head out in search of a crop that can grow even in barren land. On their travels, Hak becomes filled with grim determination while training Yona in swordsmanship. Yona notices that he's acting differently and tries to cheer him up, but what Hak does next leaves her stunned!