"The World of Music" is under the rule of the Lord Demon. The important treasure, "the Jewel of the Sound", was stolen by the Lord Demon, who injected the Negative Energy, turning it into the "Jewel of Negativity" and unleashing it all over the world. Anyone who comes in contact with it is transformed into an evil. The risk is that music throughout the universe is finally destroyed and everything ends up under the control of the Lord Demon. To save the World of Music, the Fairies of the Rhythm appear at the Miracle-Miracle, three young music idols. Thanks to the help of the Fairies of the Rhythm, Miracle-Miracles become the heroine-warriors Miracle Tunes, who fight to purify the Jewel of Negativity into the original "Jewel of Sound" through the power of music.