The origin of Arima Hot Springs, famous as the oldest working spa in Japan, dates back to the age of mythology. The Nihon Shoki that chronicles Japanese history tells of visits by the Emperors Jomei and Kotoku, and Onsen-ji Temple that was built by the monk Gyoki in the Nara Period. In the Kamakura Period, the monk Ninsai visited the area and built twelve lodgings for the twelve generals that protect the Buddhist god of medicine, Yakushi-nyorai. Moreover, the warlord Hideyoshi Toyotomi was fond of the area and visited here often. The bath and other unearthed artifacts associated with Hideyoshi can be viewed along with an introduction to the history and culture of Arima at the Taiko-no-yudono Museum.