Nishiyama Onsen Yushima no Yu

Yushima no Yu has two outdoor tubs, one round and stone, one wood, and no indoor bath at all. The water runs on the cool side, gentle enough for a long soak, though with no indoor option winter visits take a bit more resolve. It's sulfur water, kept flowing fresh, kakenagashi (掛け流し) rather than recirculated, and mild enough that there's a small tap by the baths where you can drink it, with a faint egg-like sulfur smell. Instead of showers, the rinse water runs through a wooden channel and you scoop it out by hand, a setup one visitor likened to a shrine's purification font. The baths sit above the Hayakawa river in Hayakawa town, deep in Yamanashi's mountains, and the facility is run by the town itself. It has a handmade, unpolished feel, older fittings kept very clean, plus a few rental cottages out back around a small garden.