Paper Mario/Chapter 8: A Star-Powered Showdown

Star Way
After talking with the final Star Spirit, start the long journey back down Shiver Mountain, all the way to Shiver City. As you pass the save block just outside Crystal Palace, you can step of the side of the cliff to find a star piece.

Go to sleep in the Toad House in Shiver City, and when you wake up there will be a bunch of items on the floor. Go back through the pipes and into Toad Town (using the shortcut), and north to the very top of Shooting Star Summit. Don't bother buying any items in Toad Town, since there is a much better shop in Star Haven.

Here, you will be able to take Star Way all the way to Star Haven. Use Sushi's water attacks to defeat the Embers along the way. You may also want to re-equip the Ice Power and Fire Shield bages.

Star Haven
On the lower level of Star Haven, there is the star's version of Toad House, and at the top of the castle is a shop with several high-powered items.