The Main Storyline of Kirby Star Allies begins with a mysterious cloaked figure casting a spell on a large crystal heart in a location far, far away from Planet Popstar, the home of Kirby. This causes countless Jamba Hearts to scatter across the universe as a result, corrupting anyone the come in contact with. When one comes in contact with Kirby, however, it allows him to use Friend Jamba Hearts to cure those of the evil corruption in order for them to join his team.
After this occurs, Kirby notices a number of Waddle Dees carrying food to King Dedede's Castle, which just so happens to be shrouded in dark clouds. At first, it appears as though King Dedede, the arch nemsis of Kirby, is up to no good again. Having a sense that King Dedede is causing all this trouble, Kirby begins the journey to stop him once again. After defeating King Dedede, it appears as though Kirby and others have already solved the mystery and have vanquished the culprit. However, this is only the beginning of this epic tale, as things take a dark twist once Dedede have been defeated and cured of the corruption caused by a Jamba Heart.
After then traveling through many planets and even deep space in general, Kirby will discover that the person behind the Jamba Hearts being scattered throughout the universe was Hyness himself, the cloaked figure from the beginning of the story. Apparently, Hyness is looking to use the Jamba Hearts, with the help of his three Mage Generals, to resurrect the dark god, the destroyer of worlds by the name of Void Termina. It is up to Kirby to not only stop Hyness and his three Mage Generals, but also Void Termina himself once all is said is done.
Prepare yourself for one heck of an adventure!