Whilst running to the first day of her new school, the happy-go-lucky Miyuki Hoshizora encounters a fairy named Candy, who leaves behind a pink book. As Miyuki has trouble introducing herself to the class, her classmate Akane Hino helps her to break the ice. As Miyuki checks out the library later that day, she discovers a mysterious entrance, taking her to a strange place where she learns Candy is being chased by a wolf named Wolfrun, who starts making the people in the town fall into despair and steals their 'bad energy' with a goal of ressurecting someone named Pierrot. As Miyuki strives to protect Candy, she is given a magical item known as the Smile Pact, using it to transform into a PreCure named Cure Happy. As Miyuki becomes reluctant to fight, Wolfrun summons a monster known as an Akanbe to fight against her, but with help from Candy, Miyuki manages to realise her power and defeat it, receiving an item known as a Cure Decor.