The northernmost kingdom of the Twelve Kingdoms, Ryuu is one of the four " central" kingdoms and borders the Black Sea along with En and Kyou. The capital. The Twelve Kingdoms is a Japanese series of light novels written by Fuyumi Ono and illustrated by Akihiro Yamada. The first entry in the series called "The. It has been suggested that this article be merged with The Twelve Kingdoms. is the first novel in The Twelve Kingdoms fantasy series written by Fuyumi.