The volcano Mt. Aso is one of the reasons Kumamoto Prefecture has long been called "Hi no Kuni," or The Land of Fire. It consists of five cones, one of which is still active. The physical situation of the peak Nakadake makes it the only live volcanic crater in the world that tourists can safely look down into.
A series of violent eruptions ending fifty thousand years ago ejected so much material that the ground collapsed for kilometers in every direction, creating the world's largest caldera. Later activity produced the present cones in the center, and there are now towns and fields and roughly eighty thousand people living inside the resulting space.
Seen from the point Daikanbo on the northern caldera wall, the five peaks align in a shape resembling the sleeping Buddha; smoking Nakadake makes his navel.