Okutsuso

The 'locked bath' where alkaline water bubbles up through the granite riverbed beneath you — a registered-heritage inn of just ten rooms, with a new modern kitchen and prices that have climbed fast

Okutsuso opened in 1927 after a fire destroyed its predecessor, on the introduction of the statesman Inukai Tsuyoshi, and the woodblock artist Munakata Shikō stayed and left works here; the building has been a registered tangible cultural property since 2018, with renovations every couple of years. Its fame is the Kagiyu, the 'locked bath': the Tsuyama lord once locked it to keep villagers out. Its floor is one continuous granite slab with the Yoshii riverbed, and alkaline water at about 42°C (pH 9.3) bubbles up from under the rocks — not piped in, not heated, not diluted. A second bath, the Tachiyu, is a natural rock hollow about 120cm deep where you bathe standing; both swap between men and women, and two private baths are free for guests, 24 hours, no booking. Japanese guests rate it 4.58 across 330 reviews on one major site and 4.60 on another, with baths highest. The kitchen was overhauled in February 2025 under a Michelin-starred adviser (the inn's claim), with Chiya beef shabu-shabu cooked in the spring water, matsutake, boar and Matsuba crab in season; some loved the new style, others felt it lost its charm. Complaints centre on value: prices two to three times what they once were (about ¥50,000 per person, one 2024 blogger budgeted), a cramped cheapest room, thin staffing, no shower at the annex rooms' roofless open-air baths, and a car almost essential.