Nishiyama Onsen Keiunkan Nishiyama Onsen Keiunkan Nishiyama Onsen Keiunkan (西山温泉慶雲館) is a hot spring hotel in Hayakawa, Yamanashi Prefecture, Japan. Founded in 705 AD by Fujiwara Mahito, it is the oldest hotel and one of the oldest companies in operation. In 2011, the hotel was officially recognised by the Guinness World Records as the oldest hotel in the world. It has been continuously operated by 52 generations of the same family (including adopted heirs) for over 1,300 years. The Keiunkan lies at the foot of the Akaishi Mountains. Since its foundation the hotel has had all its hot water sourced directly from the
Onsen tamago broth and soy sauce. The traditional way of cooking "onsen tamago" is to place eggs into rope nets and leave them in a hot spring, with water that is approximately for 30 to 40 minutes. Crack open the shell and serve the egg in seasoned "bonito dashi" (Japanese stock) for breakfast, or in a light sauce made with mirin, dashi and soy sauce with chopped spring onions sprinkled over the top. Onsen tamago Onsen tamago ( or ) is a traditional Japanese low temperature egg which is originally slow cooked in the water of "onsen" hot springs in Japan. The