During the Edo period, the hot springs at Shibu Onsen were a spa for the samurai retainers of the Sanada clan. The natural waters that supply Shibu Onsen’s nine public bath houses are rich in minerals. Nanamisao No Yu’s waters have a high amount of iron content, which gives the bath a distinct smell. According to legend, this bath house’s water can heal bodily injuries, such as broken bones and spinal injuries. Visitors to Shibo Onsen must stay overnight at one of the local ryokans (Japanese inns) to access this bath house and the other 8 throughout the town. Ryokans will provide a key for guests to unlock the bath houses, which are accessed and maintained by locals.