Puff and Aroma explain to Haruka, they got separated from Kanata after the Hope Kingdom was attacked by Dys Dark, led by a witch named Dyspear, entrusted with finding the three Princess PreCures who possess the Dress Up Keys. As Haruka decides to train hard to become a proper princess, student council president Minami Kaidou finds a Dress Up Key washed up on the beach. After observing Minami's graceful elegance, Haruka asks her to teach her how to do ballet so that she can become more princess-like. Despite the strictness of the lessons, Haruka continues to work hard, only to end up spraining her ankle whilst attempting an advanced move. While treating her injury, Minami confesses that she is far from perfect, only possessing her ballet skills from training hard as a kid, expressing her joy that someone asked her for lessons. Later, as Close targets a boy yearning to be a soccer star to create a Trophy Zetsuborg, Minami spots Haruka transforming into Cure Flora as she goes to fight against it. With Haruka's sprained ankle leaving her at a disadvantage, Minami's desire to protect her gives her the ability to transform into Cure Mermaid and defeat the Zetsuborg. Just as Haruka and Minami are about to celebrate their new partnership, Puff and Aroma discover that the third Princess Perfume in their possession has gone missing.
入学式に遅刻して落ち込むはるかは反省して草むしりをするが、その時、バレエを練習する海藤みなみを見掛ける。生徒会長で学園のプリンセスと呼ばれるみなみに、はるかは「バレエを教えてください」と願い出る。
