Coult, the prince of the kingdom of Loon, is living a happy life with his father King Stephan and many retainers. He is cheerful, bright, tender-hearted, and gifted by the god Aganade. Coult’s mother Galatea (the daughter of Aganade) married King Stephan. However, Medusa, the daughter of the evil spirit, was envious of her happiness and turned her into a statue together with many villagers when Coult was still a baby. In order to save the other villagers, Stephan pledged allegiance to Medusa, and was forced to promise to make Coult do the same on his 8th birthday.
When the day arrives, Coult declares that he will defeat Medusa and revive the people who were turned into statues. He sets out on a long journey to search for the daughter of the evil spirit.

(Source : nipponanimation.com)