There are 86 active volcanoes in Japan today, the most active of which are those in Kyushu notably Aso, Sakurajima and Unzen. However, Mt Asama to the northwest of Karuizawa also ranks with Aso as one of the most active volcanoes.
Kirishima‘s Volcanoland. In a small area of Japan called the Kirishima-Yaku National Park is an amazing collection of 23 volcanoes, 15 craters, and 10 cater lakes. Visitors usually make Ebino their base for exploring Kirishima. Karakuni-dake is the higest peak in Kirishima that dominates the plateau and hot steam hisses out and of the mountainside and of course sulphurous fumes from the many vents. The second highest peak, Takachiho-no-mine, is, according to legend, the place to which the sun goddess descended to found Japan. Visitors often hike the many trails around here not only to view the fabulous forest with its unique eco-system as well as to see the beautiful large crater lake (there is a campsite on its northermost shore).
Mt Aso. Mount Aso is the largest volcano in Japan, and one of the largest in the world. JNTO and other tourist agencies in Japan tout Mt Aso’s caldera as the largest in the world – however, the ranking of widest or largest caldera varies depending on the method, whether width, length of diameter, circumference or volume are calculated – say the vulcanologists. An erruption that took place from 300,000 to 90,000 years ago created a huge caldera, 25km across north to south and 18km across east to west. Its circumference is estimated between 80 and 120km. The mountain is a typical complex volcano composed of an outer rim with a total circumferential length of 128 kilometers, a caldera (circular volcanic basin) with seven towns and villages inside it and five mountains (Aso Gotake) on the central plateau including the active Mt. Naka-dake, one of the major volcanoes of the world. The 1,506-meter-high summit of Mt. Naka-dake, where the air is filled with the smell of sulfur can be reached by a ropeway. Tourists at the summit can take a close-range look at the dynamic fumes rising from the crater which extends about l kilometer north and south and about 400 meters east and west and has a perimeter about 4 kilometers long. Since it is an active volcano, shelter dugouts are provided around the crater. Read this field trip account at Peaks and Valleys to know more about Mt Aso. Access: From Tokyo, it takes an hour and 30 minutes from Tokyo Haneda Airport to Kumamoto Airport. From Osaka it is an hour from Osaka Itami Airport. Then 50 mins by bus from Kumamoto Airport to Kumamoto Station. Trains from Kumamoto take 1 hr 20 mins to Aso – from Kumamoto Station to Hitoyoshi Station by an Express Train on the JR Main Kagoshima Line-Hisatsu Line:(1,080yen) and 1h30min to Takamori (1,190yen). Direct trains from Beppu take about 2h (￥3,440), but are limited to 4 per day. Kyushu Sanko has buses between Kumamoto and Beppu that stop at the crater of Mount Aso. JR Kyushu Bus has buses between the Aso region, Beppu, Yufuin and Kurokawa Onsen. / Combine visit to Aso with a visit to the hotsprings of Kyushu. Visit also the Aso Volcano Museum in Kusasenri Meadow. (scroll up page to the Geological Museums listing for a detailed description of the museum).
Sakurajima, in Kyushu, once an island, is now a peninsula thanks to a powerful eruption of Mt. Sakurajima in 1914 that joined the island with the mainland. Lava fields flank the sides of Mt. Sakurajima, making for a lunar-like landscape. Mt. Sakurajima, which rises magnificently above Kinko Bay facing Kagoshima, still emits fumes of steam and occasionally soot and ash.
Mt Asama. Access and other info here.
Climbing Mt Fuji, icon of Japan. Mt Fuji, a dormant volcano, is described in many travel guidebooks as the most beautiful volcano in the world. Lake Kawaguchi in Hakone is the most popular base for climbers, though you can stay at the resorts beside any of the lakes. For access and info see this link.
Mt Nasu (Nasu-dake), 1,917 meters above sea level, is the main peak of the Nasu Volcano in Nasu and Shiobara Highlands, and has a crater approximately 100 meters wide and 20 meters deep that pours out rich smoke with steam. Nasu and Shiobara: A highland area extending from the foot of Mt. Nasu-dake, with the eleven hot springs of Shiobara dotting the valley of the Houki-gawa River. The highland area extending from the foot of the Nasu Volcano is dotted with hot springs including Yumoto, Takao, and Omaru. Together they form the Nasu-onsen-kyo Hot Springs Village, renowned in Japan as a resort offering recreational facilities for golfers and skiers, and for tourists, who visit the area all year round. At the far end of the Nasu-koen highland, there rises the smoking Mt. Chausudakend, of which mountainside is reachable by ropeway. One of the tourist attractions in this area is the azeleas that cover the surface of the mountain in early summer. Shiobara-onsen-kyo Hot Spring Village is located slightly to the southwest of Nasu along the Shiobara Valley at the upper reaches of the Houki-gawa River, and is commonly known simply as “Shiobara’s Eleven Hot Springs” due to the presence of eleven hot spring sources. The valley, which offers spectacular views, particularly when the autumn tints are at their best, is also known for its two suspension bridges: the 320-meter Momiji-dai Suspension Bridge at the mouth of the Village, and the Mikaeri-no-Tsuribashi Suspension Bridge (literally “the bridge of retrospection”) along the promenade. Mikaeri-no-taki Falls is a well-known scenic spot. Access: The Nasu-kogen highlands are located at the upper reaches of the Naka-gawa River in the northern part of Tochigi Prefecture. An hour 15 minutes to Nasu-Shiobara Station from Tokyo Station by the JR Tohoku Shinkansen Line, or 3 hours 45 minutes from Shin-Osaka Station with a change at Tokyo Station, by the JR Tokaido Shinkansen Line. From the Nasu-shiobara Stn take a bus (50mins) to Nasu-yumoto; to Nasu-dake Sanroku Stn by bus (20min) and then by cable car to 5min. Nasudake Sancho.
Mt Usu (Usuzan) which erupted in year 2000, is located in Lake Toya resort part of the Toya Shikotsu National Park. Several craters opened up on the west side during the eruption. An offshoot of Usuzan is Showa Shinzan (“Showa New Mountain”). This volcano is the subject of much study by school students in Japan. It is one of Japan’s youngest mountains and had risen suddenly from a wheat field between 1943-1944. For access info on how to get to Lake Toya, see this link. For access info on how to get to Usuzan from Lake Toya, see this page. The remains of destroyed buildings, toppled power lines have been left there as a reminder of the destructive power of volcanoes. Photo of Showa Shinzan and access info on how to get to Showa Shinzan can be found here.