Located on the prefectural borders of Gunma, Nagano and Niigata prefectures, this large dam lake is 1,513 meters above sea level, 25 meters deep, and around 12 kilometers in circumference. Visitors can enjoy a different landscape every season due to it being surrounded on both sides by 2,000 meter high mountains. Early summer and early fall is particularly breath-taking. In fall, the lake perfectly reflects the beautiful surrounding autumnal leaves. Over 300 different alpine plants can be enjoyed here, such as the pale beauty of the white Japanese wood poppy, and the vivid yellows of the Nosorikisuge flower.