ロケット修理のために、ヤンヤンさんの故郷のプルルン星にやってきたよ！

プルルン星は水に包まれた星で、まるで大きな水族館みたい！

きれいだなぁ～★

見て見て！サンゴのそばにたくさんお魚がいるよ！

せっかくこんな素敵な星に来たんだから、わたしたちもお魚たちと泳ぎたいよ～……。

えっ、ヤンヤンさんが持っている「へんしんじゅ」を使うと、人魚の姿になれるの！？キラやば～っ☆

さっそく変身して、ロケットの外にレッツゴ～！

Arriving on Yanyan's home planet Pururun, the girls receive pearls from Yanyan allowing them to transform into mermaids and swim underwater. However, they are soon pursued by Eyeone, who swears vengeance against Yuni for deceiving her and attacks with a robot. Although Yuni is shaked up by Eyeone's words, Hikaru gives her the encouragement to beat her. The girls eventually arrive at the core of the planet, where they can get their rocket repaired.