Mount Belenus

Mount Belenus (known as Mount Fuji in Japan) It's at the highest point in Electopia

Megaman Battle Network 5
The Nebula HQ is in the crater of Mount Fuji according with Chaud/Baryl in Megaman Battle Network 5

Megaman Star Force 3
the WAZA HQ is in the crater of Mount Fuji according with MegaMan Star Force: Official Complete Works