Surrounded by a forest and a gated entrance, the Grace Field House is inhabited by orphans happily living together as one big family, looked after by their "Mama," Isabella. Although they are required to take tests daily, the children are free to spend their time as they see fit, usually playing outside, as long as they do not venture too far from the orphanage — a rule they are expected to follow no matter what. However, all good times must come to an end, as every few months, a child is adopted and sent to live with their new family... never to be heard from again. However, the three oldest siblings have their suspicions about what is actually happening at the orphanage, and they are about to discover the cruel fate that awaits the children living at Grace Field, including the twisted nature of their beloved Mama.
The Music Kingdom contains musical treasures called Sound Jewels, which together produce the "Song of Blessings." The Sound Jewels are stolen by Maou, who corrupts them into Negative Jewels. Through the Dokudoku-dan, the Negative Jewels are used to turn humans into Negative Jewelers to spread a Negative Aura for Maou to use in his plan to conquer the human world by composing an evil song. In order to recover the Sound Jewels, the goddess of the Music Kingdom sends the Fairy Rhythms; Poppun, Rocky, and Kuranosuke, to the human world to seek help.