Mt. Aso was a dormant volcano located near Kitamatsu. After they hatched and grew to maturity, the first two Rodans nested in it. The Japanese Self-Defense Force bombed the crater (against the advice of Dr. Sunagawa), causing Aso to become active once again and erupt. Later Princess Selina Salno predicted that one of the Rodans would emerge from the crater.
In the English dub of Rodan Aso is renamed Mt. Toya.