In an ancient land between the worlds of Nintendo is the mystical realm Nintendia. Every year a festival called the Imagination Fest is held, where the Orbs of Unlimited are held high. But one day, a creature known only as the Kingdom Crushers destroys the Orbs, scattering their magic, and destroys the portals. The only one(s) who managed not to escape back to his own worlds, the player(s) Mii is left to open the gates and retrieve the energy, in the form of Suns. With outside help, the Mii can open the gates and find the Suns. Monita comes to guide and gives him or her the Twinkler.
After collecting as many as possibly, the Mii takes the Suns to the lair of the Kingdom Crusher and destroys his front gates. Inside he rematches all of the bosses he fought before finding the door to the Kingdom Chrusher. Inside of the door they battle the Host, who had failed to stop them before but has grown more powerful. but after being defeated, he turns into Monita's brother, Bomita, and it is revealed that the whole time Kingdom Crusher had been turning him into a monster. They both help the Mii(s) defeat Kingdom Crusher. who falls off of his castle into th abyss.
The next year, everyone celebrates the Imagination Fest again.