Video Game appearances
In Dragon Ball Z: Buu's Fury, Goten and Trunks go in the Fukurou Forest to find one of the seven Dragon Balls. The Ninja Boss' room in the Ninja Stronghold has an area for storing all seven Dragon Balls. They defeat the Ninja Boss inside the Ninja Stronghold there to get the Six-Star Dragon Ball.
The Ninja Stronghold is a castle overtaken by nature, with many hollowed out trees acting as passageway around the fort. The Ninja Boss' room contained a pedestal for the Dragon Balls and was a tree with a statue of Shenron's head. The Ninja Key to the room was hidden elsewhere in the fort in a statue of Shenron's head.