Yunohana Onsen Tenjin-no-yu

One of four communal bathhouses in Yunohana Onsen, a small hot spring hamlet deep in Minami-Aizu in Fukushima. Tenjin-no-yu sits near the Yunohana Ohashi bridge and offers a single tub, big enough for three or four people, fed by 100% natural spring water at a temperature that can run quite hot. There's an unspoken local etiquette of adjusting the heat with the tap, and opening the windows gives a pleasant open-air feeling. It's a genuinely communal bath: shared with locals, mixed bathing, no frills.