Kuromi and Baku are imprisoned in a dungeon in Mari Land. They escape along with the Melody Key and the Melody Bow, but in their haste, forget the instruction manuals. They flee to the human world and shortly after arriving, Kuromi discovers the power of the Melody key: it makes wishes come true but in a twisted, nightmarish sort of way. If the person who wishes enjoys the nightmare, he produces one or more black notes, which Baku promptly eats. What neither one of them realize is that when 100 black notes are gathered, the Spirit of Dark Power consumes the dreams of all humanity. Because Mari Land is formed from the dreams of humans, even the incompetent king of Mari Land is able to sense the danger. He gives the Melody Takt to My Melody and sends her to the human world. Her mission is to collect 100 pink notes before Kuromi and Baku can collect 100 black notes. If she can do this, then the Dark Power will be defeated, and both the human world and Mari Land will be saved.