My Melody arrives on Earth much to the surprise of her rivals, Kuromi and Baku. Together with one of the junior high school students, Yumeno Uta, they decide to protect the dreams of the people with the help of magic.
[Edit]Kuromi and Baku are imprisoned in a dungeon in Mari Land. One day, they obtained the Melody Key, a magical instrument having dark magical powers, and escape from the prison. They head to the human world in order to get Black Notes, to resurrect the Spirit of Dark Power,by making people have nightmares. Under these circumstances, My Melody is suspected of helping them escape. She is ordered to go to the human world to arrest them and save people's dream. In Yumegaoka City, Kuromi is deceiving people, saying she will grant their wishes, but creating nightmares using the Melody Key. My Melody also arrives in Yumemigaoka City, and meet Yumeno Uta, a junior high school student. She is helped by My Melody when she falls victim to Kuromi's Melody Key. Then, My Melody starts living with her. After that, My Melody and Uta are involved in various troubles caused by Kuromi, but they solve them using My Melody's Melody Tact, a magical instrument.