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 comes face-to-face with Su-won and tells him that waging war against the nation of Xing would be disastrous. Later, she rushes back to Princess Kouren, but assassins and more dangers await in Xing! Will the Four Dragons be able to protect Yona from all who threaten her life?