The Twelve Kingdoms: Sea of Shadow

The Shadow of the Moon, The Sea of Shadow, 月の影　影の海, Tsuki no Kage, Kage no Umi is the first novel in The Twelve Kingdoms fantasy series written by Fuyumi Ono. The Japanese edition split the novel into two volumes, but the English edition combines them into one, as The Twelve Kingdoms: Sea of Shadow.

The book narrates the adventures of Yoko after being brought by Keiki to the world of the Twelve Kingdoms. Yoko finds out that she is not a Kaikyaku, an ordinary human who was swept across the sea from Japan to the Twelve Kingdoms, but a Taika - a human who was swept away to Japan from the Twelve Kingdoms before her birth and was then brought back to the Twelve Kingdoms.

The first volume is divided into eight chapters. The epilogue, the Red Book of Kei, retells the politic events between the fall of the King of Kei and Yoko's ascendance to the throne.

The book was published by Kodansha on June 20, 1992. The English language edition is published by Tokyopop under the PopFiction imprint.

Plot introduction
Yoko Nakajima's life had been fairly ordinary. Until Keiki, a young man with golden hair, tells her that she is his master, and must return to their kingdom. With the help of a magic sword and a magic stone she fights against the demons on her trail.Yoko begins her quest for both survival and self-discovery in her new land.