Manga adaptation of the novel "Yami no Moribito", which is the second novel in the Moribito series after "Seirei no Moribito". All the Moribito novels have standalone plots.

After the events of Seirei no Moribito, Balsa returns to her birthplace in Kanbal to revisit her past with Jiguro, the man who raised her. When she finds out that he has been implicated for the death of the king, she fights to clear his name, and on the way uncovers the hidden part of Kanbal.

Once every 100 years, a Water Fairy implants an egg into a person who then becomes the Guardian of Fairies. This time, the responsibility falls on Chagum, the second prince of the New Yogo Kingdom.
Chagum`s life isn`t easy. The king finds Chagum an inconvenience and attempts to have him killed. As a result, the queen asks a female guard, Balsa, to protect Chagum. In addition to this, beings from another world, known as Nayugu, constantly attack him in order to eat the egg carried in Chagumu`s body.

Centered around a girl who can control the greatest of beasts as if she was playing a musical instrument. However, she gets embroiled in a war for supremacy between kingdoms.