Mt. Daibetsu was a massive mountain range used in experiments by the Dinosaur Empire. They abducted a large number of the villagers in the nearby town and replaced much of the surrounding area with ancient plants and reduced the people to Apes using a de-evolution chemical.
Inside the mountain is a base with labs that feature defences like the Subterranean Missile Launcher Mogrow. Much of the mountain is destroyed when the Getter battle against several Mechasauruses (Boar, Giro, Bull and Doba) and destroyed the underground base.