The Yasha Crag.
The Yasha Crag (夜叉岩, Yasha Iwa) is a place where once Yasha-Zaru lived. Now his son, Yasha-Zaru Jr lives there. This crag is located in the Hida Mountains in Gifu Prefecture.
In the anime near the Yasha Crag there was a tree named the Great Elder. In the manga, the Great Elder is in a completely different location, in the Aokigahara forest. The anime authors decided to combine the two themes into one, without saying where the Yasha Crag and the Great Elder tree are located. In anime, both places were in the same area, while in manga they were in two completely different locations, which were precisely defined (Hida Mountains and Aokigahara forest).