In deep space, the leader of a mysterious cult performs a strange ritual, which causes shadowy hearts to rain down on the galaxy. The hearts corrupt the inhabitants of Planet Popstar, including King Dedede, Meta Knight, and Whispy Woods, causing them to act strangely. Meanwhile, Kirby is asleep in a field of grass when he's hit by a pink heart, giving him the power to use Friend Hearts. He then notices that something's up at Dedede's castle, and hurries on his way to investigate. Little does he know about the threat from deep space, and that he might need some help along the way.
—Anonymous