The Fairy Castle is a magical world, led by the Fairy Queen. Only the Fairy can learn magic and know how to use magic to help others. However, the evil Black Demon Fairy Xiaoyue secretly practices black magic and steals the Demon Fairy's colored stones in an attempt to seize the secret of the highest magic. As the guardian of the Demon Fairy, Xiaolan was ordered to track down the Magic Fairy Colored Stone and the Black Demon Fairy's whereabouts and came to the human world. Xiaolan hid in the music box and was accidentally taken home by a pair of little sisters Le Meiqi and Le Meixue. Xiaolan became the nanny of the Le family and began a precious friendship with Meiqi and Meixue. With the approval of the Demon Fairy Queen, Xiao Lan taught Meiqi and Miyuki magic, allowing them to become little Demon Fairies and use magic to help others. Later, the Black Demon Fairy Xiaoyue appeared and trained Yan Lili to become the Little Black Demon Fairy. The battle between the two forces of good and evil began. The Demon Fairy Prince also came to the world, and finally helped Xiaolan and the others defeat the Black Demon Fairy Xiaoyue.