Major Land is a vibrant realm of music where instruments and notes possess life. During a yearly concert, Hummy, a feline singer from Major Land, readies herself to perform the "Melody of Happiness," a tune capable of bringing joy to other worlds. Mephisto, the ruler of Minor Land, disrupts the performance and alters the score into the "Melody of Sorrow," a discordant piece that induces despair. To stop this, Hummy must locate the Precure, famous warriors driven by their love for music, and restore the original melody.
Hummy travels to Kanon Town, the residence of Hibiki Houjou, an athletic student with a musical talent, and Kanade Minamino, a diligent baker. Hibiki and Kanade, who used to be inseparable friends, now spend their time arguing and have lost contact. Their conflict is interrupted by Siren, a singer from Minor Land. When Siren transforms a significant record into a massive monster, both girls feel a deep urge to safeguard their cherished values, leading them to transform into the Suite Precure! As legendary fighters, Hibiki and Kanade must set aside their differences to defend the world's happiness.