What collectible raises Mario's maximum HP in Paper Mario: Sticker Star?

What collectible raises Mario's maximum HP in Paper Mario: Sticker Star? The answer is HP-Up hearts.

HP-Up hearts increase Mario’s maximum health in Paper Mario: Sticker Star. Each one raises his maximum HP by five points and also strengthens his attacks, making these collectibles valuable far beyond simple healing.

Sticker Star changes the series’ usual character-progression system. Battles are fought with consumable stickers, and the game does not use traditional experience points to develop Mario. Instead, finding HP-Up hearts provides a major route to permanent improvement. They are placed throughout the Mushroom Kingdom and often reward exploration or progress through challenging areas.

The name is easy to confuse with Pure Hearts from Super Paper Mario, which are story-related items in a different game. Hammer scraps are also associated with Sticker Star, but they improve Mario’s hammer capabilities rather than directly raising his maximum HP. Star Points belong to the battle-progression systems of other Paper Mario games and are not the collectible answer here.

Because an HP-Up heart improves both survivability and offensive strength, collecting them can make later areas and boss battles considerably more manageable.