Everyone becomes curious as to how Siren became a Pretty Cure, especially Siren herself, who finds she can no longer transform into a cat or change her disguise. Left confused as to where to go, she winds up at the church where Mr. Otokichi gives her comfort. Hummy finds her, but she feels she doesn't deserve to be forgiven so easily. As Hummy follows her around, with Hibiki and Kanade also offering their friendship, they are approached by the Minor Trio who create a Tree Negatone. As the Pretty Cure run into trouble and Hummy is captured, Siren stands to protect and produces a Cure Module, allowing her to transform into the Pretty Cure, Cure Beat. Using her new abilities, she rescues Hummy and defeats the Negatone. After the battle though, Siren is still unable to forgive herself and runs off again.
セイレーンがプリキュアだということが発覚した。ハミィは嬉しそうだが、響と奏はまだ信じられずにいた。どこかへ行ってしまったセイレーンを探すというハミィに従い、響と奏もその行方を探しにいく。
