Mount Aso (阿蘇山, Asosan) is a large active volcano in the center of Kyushu. The mountain's caldera, created by multiple gigantic eruption in the distant past, is with a circumference of over 100 kilometers one of the largest in the world. Surrounded by a circular rim, the caldera contains multiple rural towns and wide areas of rice fields.
In the center of the caldera stand the currently active peaks of the volcano. The main crater can be accessed and viewed by tourists, but gets occasionally closed due to high levels of volcanic gases. On the grassy slopes of the volcanic peaks graze horses and cows, making for scenic, pastoral views.