The stratovolcano Akagi (Japanese赤城 山, Akagiyama ) is one of the major mountains in Gunma prefecture in Japan. It is characterized by its long, gently sloping hillsides. The highest point is 1828 m above sea level.
Akagi is the nature park on the west side of the mountain. The andesitic volcano rises above the northern end of the Kanto Plain. The 3 x 4 km be measured, elliptical caldera contains several lava domes, which are in an aligned northwest-southeast line. The Ono- Lake is located in the north-east end of the caldera. The structure of the central crater began after the last major Plinian eruptions about 31,000 years ago. In historical times it was reported in the 9th century by some eruptions. However, reports of outbreaks in the years 1251 and 1938 must be regarded as uncertain.