The story of the anime centers around a girl named Youko Nakajima from Japan, who is suddenly transported to another world and eventually discovers that she is the queen of the kingdom of Kei. This part of the story is based on the novel Tsuki no Kage, Kage no Umi (Shadow of the Moon, Sea of Shadow). This novel, and thus anime, follow the general Monomyth pattern, but several twists and inversions of the pattern give them originality.