Manatsu and her friends decide to go on a camping trip to Minamino Island over their school's summer break. Gathering at Manatsu's, the girls discuss activities over the course of the camp, with Manatsu mentioning of a cave said to be hiding treasure and her mother, Aoi, suggesting they can relax at the beach. Following her mother's idea, Manatsu decides to show her friends the island's secret beach. The next day, Manatsu and her friends assemble to head off to their destination, but Chongire makes a Zenzen Yaraneeda out of Manatsu's suitcase to attack the city, forcing the girls to transform to engage it...