In the fantastical and ever-changing Demon Realm, the beloved Princess Luna Shadow Song has a sweet little problem—her magic is extremely unstable and often 'malfunctions.' Hoping to prepare a perfect surprise for the upcoming Demon Realm Festival of Joy, she loses control of her magic and wreaks havoc in the palace garden. With the help of Sagan, the chief minister, and Mia, her elf friend, Luna sets off on a journey to find a 'magic stabilizer.' However, Kaos, a distant relative and count who covets the throne, lays a trap in an attempt to prove that Luna is unfit to be a princess.