Yuko Mori

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.

16-year-old super-studier Nagi Umino, second-year student at the Megurogawa Academy high school, was switched at birth. On his way to a dinner to meet his birth parents, he accidentally meets the brash, outspoken, Erika Amano, who is determined to make Nagi her fake boyfriend as she never wants to actually marry. But once Nagi makes it to dinner, he finds his parents have decided to resolve the hospital switch by conveniently having him marry the daughter his birth parents raised...who turns out to be none other than Erika herself!