The first story about the Juuni Kokuki (the Twelve Kingdoms) begins in Tokyo. Yoko Nakajima, an unconfident school girl tired of being head of class, has nightmares about weird monsters every day.

Suddenly, a strange man, Keiki, shows up at school and offers to be her protector. A few moments later a giant bird, a Koucho, attacks the school. Keiki gives her a sword to defend herself, but she refuses to use it. Keiki takes her and two of her classmates away, and they flee through the reflection of the moonlight on the ocean.

The next morning, Yoko wakes up, marooned near the coast of a country unknown to her. There is no trace of her classmates or Keiki to be seen, only the sword lies next to her. When she gets to a nearby village, she finds herself arrested. Why was she brought to this alien world? Why are these weird monsters and even the villagers attacking her?

There is no Juuni Kokuki manga. This anime is based on text novels written by Fuyumi Ono. It features a complex fantasy world with a rich mythology behind it. The series tells us not only Yoko Nakajima`s story, but also stories about other people who came to live in this world.