An Oath to the Sea! Minami's Most Important Treasure!.The girls visit a seaside resort owned by Minami's older brother, Wataru, where they meet Minami's dolphin friend, Tina, and learn more about her aspirations to carry on the family business. Pained by the bonds shared between Minami and her brother, Twilight has Lock target Wataru to create an Orca Zetsuborg, while Shut creates Octopus Zetsuborg to fight against Haruka and Kirara, who learn of a Dress-Up Key nearby. As Minami struggles against the Orca Zetsuborg, she is protected by Tina, who once saved her life when she was young. Determined to save Tina, Minami awakens the power of the Bubble Miracle Dress-Up Key, allowing her to heal Tina's injuries and help the Cures defeat both Zetsuborgs.