As Siren comes up with an idea to take advantage of Cure Muse's appearance, Hibiki and Kanade continue to struggle in their hunt for Muse's identity, trying to lure her out with a radio broadcast, with Seika, who denies being Muse, meeting with them for comfort. Meanwhile, Muse allegedly calls out Hibiki and Kanade, but in reality, it is Siren who steals the girls' Cure Modules and throws them into the sea. However, they are saved by the real Muse, who reveals the fake. Siren creates a Seaweed Negatone to fight against Muse, whilst Hummy recovers the girl's modules so they can transform and work with Muse to defeat it.
響は奏と一緒に学校でキュアミューズを探すことにする。きっと音楽を愛する心を持っている子だろうと、2人は予測していた。しかし、簡単には見つからない。そんななか、再びキュアミューズが現れる。
