Echigo Nagano Onsen Rankeisou

Rankeisou is a single ryokan on the Ikarashi River in the Niigata hills, part of the Nihon Hitou wo Mamoru Kai group of secluded hot springs. Bathing runs on the inn's own spring: an indoor bath plus two hillside outdoor tubs, ishiyu (石湯), built from river stone, and fukayu (深湯), a deep tub you float in rather than sit. The water is clear and quite salty, with a faint clinging feel on the skin, and it's kept mild and lukewarm rather than piping hot. Overnight guests get the hillside baths to themselves each evening; day-trippers bathe there in gender-alternating shifts instead. The spring is drinkable too, savory with a kombu-like taste, and gets poured warm with hojicha at the lounge irori. It's mild enough that families with small children come here regularly.