At 2,568 meters above sea level, Mt. Asama is an active volcano which lies on the borders of Gunma and Nagano prefectures. When Mt. Asama erupted in 1783, the lava flowed from the volcano and spread throughout the northern and eastern sides and down to the base of the mountain, turning into rocks of all shapes and sizes after cooling down. This vast area is now called Onioshidashien/Asamaen and is part of the Joshinetsu Highland National Park, a place where you can see these rocks up close.