The Moon Child is a being of legend, along with the Black Monster. In fact, the two are closely related. "Count 108 years, and when the Moon That Never Sets glares red, the Moon Child descends to the earth to fill the world with holy bliss." Legend has it that the Moon Child is a holy being that will bless the world and create a utopia. However, another being, the Black Monster, hates and despises the Moon Child, and kills it every time it is born. It is said that it can't stand its holy light.
Later the true story of the Moon Child is revealed. The creator Soa made the world using the Divine Tree, which bore fruit from which all life sprung. There were 108 fruits, and 107 of them were born. However, the 108th was meant to be the God of Destruction, the being that destroys the world. The powerful Winglies found out about it, however, and separated the mind and the body of the god. They trapped the mind in the Crystal Sphere, which Melbu Frahma used to sap power from the gods to rule the humans. In his battle with Zieg, the Crystal Sphere was destroyed, leaving the mind of the god to wander to a different body, making the transmigration every 108 years. Thus the story of the Moon Child was born.
However, one person discovered that the Moon Child was really a force of destruction, and determined to kill it to save the world. Ever since, this Black Monster has had to kill 107 Moon Children to save the world. Finally, it tried to kill the last one 18 years ago, Princess Louvia. However, it mistook this child for the real Moon Child, Shana. The party must then track down Shana to stop her from becoming the God of Destruction and destroying the world.