The Hero's Heart is a star-shaped object that pops out of Kirby when he is split into 10 smaller copies by Necrodeus. It hovers in the air and guides the Kirbys through their adventure to defeat the death god and restore themselves to one again. It is heavily implied that this heart is Kirby's spirit, and contains his thoughts and wishes, especially since if all the mini-Kirbys perish, the heart bursts and vanishes.
The Hero's Heart serves as the means for the player to control the Kirbys, as they cannot be controlled on their own. When the player taps the stylus on the screen, the heart appears, prompting any Kirbys nearby to approach it. The heart can also be used to toss the Kirbys at objects, and pull them all into the air using magical force.