One day, the Tropical-Rouge Pretty Cure receive an amazing invitation from the Land of Snow, Shantia. They're holding a ceremony to celebrate Sharon becoming the new queen. They all depart to the sparkling world of snow. Laura, who wants to be the queen of the Mermaid Kingdom, befriends Sharon who gives her a beautiful ring. But just as they decide to keep a promise, a mysterious monster suddenly appears and locks everyone inside of the kingdom. When it seems like all hope is lost, the Heartcatch Pretty Cure team rush in and give them all a boost of motivation. And when their feelings become one, the ring transforms into the Snow Heartful Ring...