In a land far away, the sun and moon shine only thanks to heroic Guardians. But when the most unlikely little creature, Mune, is chosen to be the new Guardian of the Moon, a series of unfortunate events occur, leading the sun to fall into the hands of a disgraced Guardian seeking revenge. Teaming up with Sohone, the swaggering new Guardian of the Sun, and Glim, a fragile yet witty girl, Mune and his friends must embark on a magnificent adventure to rescue the sun and save their world. If he succeeds, Mune will be a legend forever more.