Nodoka and Chiyu keep reminding Hinata to keep their Pretty Cure identities a secret, as she nearly lets it slip whenever her friends talk about the monster attacks. As they visit the town's aquarium, hilarity ensues when it appears that Chiyu and Hinata's personalities clash with each other. But then they notice that Pegitan was missing as he is running away from the aquarium staff who mistook him for one of the birds in captivity. While the trio search for him, things become more problematic when Shindoine creates a MegaByogen and accidentally captures Pegitan in the middle of the attack...