is an active stratovolcano in the Shikotsu-Toya National Park, Hokkaidō, Japan. It has erupted four times since 1900: in 1910 (which created Meiji-shinzan), 1944-45 (which created Shōwa-shinzan), August 7, 1977, and on March 31, 2000. To the north lies Lake Tōya. Mount Usu formed on the southern rim of the caldera containing the lake.