Nodoka Hanadera, a middle school student who is sickly yet optimistic, has recently relocated to Sukoyaka City, an area renowned for its healthy atmosphere. She quickly befriends two classmates: Chiyu Sawaizumi, who is gentle but athletic and comes from a family that operates a hot spring inn, and Hinata Hiramitsu, the bubbly and fashionable daughter of a veterinarian. Shortly after her arrival, Nodoka discovers a sick puppy in a forest, accompanied by three magical talking animals: Rabbirin, Penguitan, and Nyatoran. They inform her that the puppy, Princess Latte, can only be healed by defeating a nearby monster called a "Mega Byogen" and purifying the land it has corrupted. Although she lacks power, Nodoka refuses to surrender and allow Latte to suffer. Impressed by her resolve, Rabbirin makes a pact with Nodoka, enabling her to transform into a hero known as a Precure. Taking on the identity of "Cure Grace," the revitalized Nodoka battles the Byogen and heals the earth, thereby curing Latte. As the Byogen and their leaders persist in their attacks, Penguitan and Nyatoran also locate their partners in Chiyu and Hinata, granting them the powers of "Cure Fontaine" and "Cure Sparkle" respectively. Now, the three Precure and their animal companions must stop the Byogen and protect the earth from their infections!