Mount Asahi is an active stratovolcano, in height that arose southwest of the Ohachi-Daira caldera. The Japan Meteorological Agency gave the region rank C in volcanic activity. The volcano consists mainly of andesite and dacite, Holocene volcanic non-alkali mafic rock less than 18,000 years old. In addition to the main peak, there is a smaller volcano emerging from the southeast shoulder of the mountain, .