Gusty Gulch is a small wasteland where peasant Boos and "hyper" versions of other creatures live in Paper Mario. It is located in the east of Forever Forest and can be reached by passing the back gate of Boo's Mansion. The area consists of three parts: the Windy Mill at the base of the gulch, a village where the peasant Boos live, and some cliffs in the east. Tubba Blubba's Castle can be found at the end of the cliff area.
The Boos suffer attack from Tubba Blubba until his defeat. When Mario first visits the village, Tubba Blubba comes along and eats one named Stanley. Later in the chapter, Mario defeats Tubba Blubba in the Windy Mill area, therefore freeing the Boos. It is revealed that the Boos actually live in the abandoned village, and that they did not build the town.
Gusty Gulch is similar to Twilight Trail in Paper Mario: The Thousand-Year Door, containing a dry landscape, dead trees, and Hyper Clefts. The in-game map description reads, "Boos like to hang around this deserted gulch. On the ridge is the castle of the Invincible Tubba Blubba."
In Chapter 3, Mario and Lady Bow head for Tubba Blubba's Castle to defeat Tubba Blubba and help the Boos, for which Lady Bow promises to give him Skolar as a reward. When they pass the village, they learned that Tubba Blubba has come there the day before and eaten Herbert. Not short after that, Tubba Blubba himself arrives to eat the Boos. The Boos hide, and so do the two with Lady Bow's Outta Sight ability. However, Stanley is late and is caught and eaten by Tubba Blubba.
Later in the chapter, Mario and Lady Bow are caught stealing the Yakkey in Tubba Blubba's Castle. Six Boos from the Gusty Gulch village come to help Bow and, after the two come out, block the door to stop Tubba Blubba from going out. The two run away, passing the village and opening the Windy Mill at the base of the gulch with Yakkey. They find that Tubba Blubba's secret is his heart hiding deep down the mill. After the heart is defeated, it jumps out of the mill and reunites with Tubba Blubba who has chased down. This makes Tubba Blubba no longer invincible and easily beaten.
After Tubba Blubba is defeated, the Boos he has eaten are released from his body and return to Gusty Gulch, Stanley and Herbert included. The Boos at Gusty Gulch will write Lady Bow an admiration letter, which the player can read at the Post Office in Toad Town. The letter thanks her for her effort, saying that they are throwing a party and Bow is invited to it after she is done with her quest.
At the end of the game, two Boos come to the party at Peach's Castle, one from Boo's Mansion and one from Gusty Gulch. The latter mentions that the Boos are going to have a wedding ceremony at Gusty Gulch.
There is a Save Block and a Heart Block in the village, as well as a hidden (but not invisible) block in the easternmost house in the first scene containing one coin. One of Koopa Koot's favors involves retrieving a Package from a Boo in the Gusty Gulch village. In the cliff area east of the village, there is a Letter by a branch on the ground which can be delivered to Igor in Boo's Mansion. When he receives it, he mentions that it is an order from Gusty Gulch.
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