Siren is denounced as the leader and runs off, with Bassdrum becoming the new leader of the Minor Trio. Meanwhile, Hibiki and Kanade decide to enter a music contest together. On the day of the contest, they realise they don't have a piano to perform on, but their friend Waon Nishijima helps them out. However, it is soon revealed that the contest is a trap laid out by Bassdrum who spreads the Melody of Sorrow and creates some Cymbal Negatones. As Hibiki and Kanade struggle to fight against it, a mysterious masked Cure known as Cure Muse appears and ensnares the Negatones, allowing Kanade to purify them.
町で音楽自慢大会が開かれることになった。響と奏も張り切ってピアノの練習をする。だが、それらは全てバスドラたちの作戦だった。ネガトーンに追い詰められて大ピンチに陥ってしまう2人だったが...。
