In Paper Mario: Sticker Star the typical RPG mechanics are gone: without experience points and level, there’s no way to improve Mario’s Hit Points other than finding the HP-UP Hearts. Each Heart will improve Mario’s Hit Points by five points: with 16 Hearts total Mario’s HP can reach 80. Given that some common enemies and bosses can be quite though, it’s really important to find them as soon as an area is available for exploration.
The first heart is located in the windy garden in 1-2: replant them by using Ice and Fire Flowers and you’ll be given the heart as a thank you gift. Another heart will be obtained after defeating the Big Buzzy Beatle at the end of 1-4.
In 2-1 there’s a pyramid hidind a platform, where the heart is located. Get to the top of the pyramid, slide down using the ramp on the left and jump over the gap. The second heart is close to the right rear foot of the Sphinx: walk towards the background to drop from a ledge and get the heart. The last heart for world 2 is in 2-4, in a sarcofagus on the back wall of the room behind Door 3.
The first heart is in 3-1 and you’ll get it after cleansing the forest. The second HP hearts is in 3-3, behind a hidden door located up the ramp in the upper floor in Wiggler’s Treehouse. The third one is in 3-8, hidden behind a tree on the forest floor: to get it simply cross the poisoned stream and get to the left. The fourth heart is near the second pool in 3-9: you’ll find it behind the steps on the left side. The last heart in 3-10: after cleansing the forest again you’ll finde the HP heart in the storage room.
The first HP heart is in 4-2, on a platform near the second frozen river. The last one is in 4-3 and you’ll have to bactrack to this area after completing 4-5: sit down with the forebear and the steward will offer you the heart.
In 5-1 you’ll find the first heart in cave near the carnivorous flower, in the temple courtyard. The last one for this world it’s in 5-6, near the lift in the Volcano, on the second floor.
Once you’re done with the Tod Rescuing quest you can find another heart in Decalburg’s Residential Area: read the postcards in the house to the right and get the heart
After finding the Warehouse door and placing it where it belongs, get to the upper floor to get the Final HP Heart.