For hundreds of years, Japan was in a state of constant turmoil. But now, the country thrives under the rule of the Aoki family. Kimiko Aoki is a Japanese princess, and royal advisor to her brother Kaito Aoki, who is the current emperor of Japan. Their mother Ei serves as Kaito's assistant and mentor. Their family line has held the throne for over a century, but with Emperor Osamu's death and Kaito's recent disappearance, Kimiko and Ei are hidden behind a curtain of shame and fear. If the population finds out that Emperor Kaito is missing, they will panic and call him a coward. And cowards are a black stain on Japan's reputation, doomed to be treated as traitors. Amidst all this, terrible news is occupying the mind of every Japanese citizen-the Mongols are invading. Without Kaito to take charge and lead the country's forces against the enemy, there is no hope. Kimiko's best friend Yukio Yoshida is doing is best to help citizens evacuate the captured territories, but he wants to do something more. Yukio hears from a refugee that there are rumors of a young man of imperial blood being held by the Mongols. Clutching on to this shred of hope, Yukio quickly persuades Kimiko that they must take action. The pair hastily make the twenty-mile journey through enemy territory to rescue Kaito at Japan's borders, praying that it's not too late. If the emperor cannot be found before the Mongols reach Tokyo, Japan will be crushed by Kublai Khan's iron fist. Can Kimiko and Yukio stop the spiral of panic and rescue Japan before it's too late?