"The Twelve Kingdoms" is a fantasy novel series written by Fuyumi Ono. It follows the journey of Yoko Nakajima, a high school student who is transported to a parallel world consisting of twelve kingdoms. Each kingdom has its own unique culture, politics, and magical elements, and Yoko must navigate this complex landscape while discovering her own identity and purpose. The series explores themes of self-discovery, leadership, and the struggle between good and evil. As Yoko encounters various characters, including Keiki and Shoryu, she learns about the responsibilities of ruling and the importance of making difficult choices in a world filled with challenges.