The kingdom of Märchenland, where various characters from fairy tales reside, is attacked by Pierrot, the evil emperor of the Bad End Kingdom, who seeks to direct the world towards its worst ending and steals the Cure Decors, which power the Queen of Märchenland, Royale. Using the last of her energy, Royale manages to seal Pierrot away. However, his minions seek to revive Pierrot by harnessing the Bad Energy from the people of Earth.

In order to protect Märchenland and regain her strength, Royale sends out five mystical lights to Earth and orders a fairy named Candy to search for five legendary warriors, the Pretty Cures. Arriving in the town of Nanairogaoka, she encounters Miyuki Hoshizora, a new transfer student, who soon gains the power to become Cure Happy. Joined by her new friends, Akane Hino, Yayoi Kise, Nao Midorikawa and Reika Aoki, who become Cure Sunny, Cure Peace, Cure March and Cure Beauty respectively, Miyuki and her friends form the Smile PreCure in order to recover the Cure Decors, save Märchenland and protect everyone's happiness.

(Source: Wikipedia)