The PreCure girls are locked in the world of "today." The character who holds the key to the story is Miracurun, the spirit who is in charge of "tomorrow" and has the mysterious power to create Miracurun Light. Meanwhile, Refrain, the spirit in charge of "yesterday" who is an enemy aiming at Miracurun, appears and tries to change the world to "a world where tomorrow will never come" by repeating the same "today" every day.

[Source: Crunchyroll]