A sign advertising the option to boil an egg at the Beppu Hot Springs, Beppu, Japan. The city was founded on April 1, 1924, and is famous for its onsen (hot springs), which are regarded as sacred. Beppu is Japan's onsen capital with the largest volume of hot water in the world apart from Yellowstone in the United States and the largest number of hot spring sources in Japan. Beppu contains nine major geothermal hot spots, which are sometimes referred to as the "nine hells of Beppu".