Yujimata Onsen Yamagataya Ryokan

Just down the lane from Izumiya, Yamagataya has the same floor-springing alkaline spring and a similarly long pedigree, the bathing culture here goes back to the Muromachi period. Its signature is the natural rock bath (岩風呂, iwaburo): water wells up through cracks in granite into a cave-like stone basin, and the whole thing is mixed for most of the day. The inn is simple, the mountain valley setting is remote and peaceful, and the spring has no additives whatsoever.