Major Land is a vibrant realm of music where both instruments and musical notes come to life. Hummy, the feline songstress of Major Land, is poised to perform the "Melody of Happiness" during a yearly concert event. This song is so powerful that it's capable of spreading sheer joy even to distant worlds. Unfortunately, Mephisto, the ruler of Minor Land, crashes the event and alters the score to create the "Melody of Sorrow." This dissonant composition is designed to evoke feelings of despair when performed. Hummy is charged with preventing Mephisto's plans by seeking out the Precure – elite warriors with an unwavering passion for music, to help her recreate the Melody of Happiness. Hummy lands in Kanon Town, where Hibiki Houjou, a talented athlete with a passion for music, and her best friend, studious baker Kanade Minamino, reside. However, they've become estranged and are now constantly at each other's throats, which Hummy discovers as she tries to connect with them. Unfortunately, their reunion is interrupted by the songstress of Minor Land, known as Siren, who destroys an important record and transforms it into a monstrous creature. With this incident, the hearts of the girls are moved with a strong desire to protect what they hold dear, causing them to transform into the formidable Suite Precure warriors. To defend the happiness of their world, Hibiki and Kanade must put aside their personal differences and work together in harmony.