Itamuro Onsen Daikokuya

A hot-spring inn founded in 1551 that doubles as a contemporary-art museum, with silky alkaline water flowing through every bath — calm and unusual, but rooms are old and the baths small

Daikokuya has been an inn at Itamuro since 1551 and calls itself an inn 'for rest and art'. Under its former head it built a long relationship with the artist Kishio Suga: since 1991 his works have filled the grounds, a warehouse museum of about 300 pieces opened in 2008, and the salon hosts a new exhibition every month, with a daily guided tour at 10:00 (Japanese only). The inn has 31 rooms in three buildings, all south-facing with floor heating, and meals come to your room — daily-changing Japanese cooking built on sesame, beans and kelp with no chemical seasonings, local river fish and Nasu wagyu. All baths are 100% free-flowing alkaline simple spring (pH around 9.4) with no added water, recirculation or chlorine; bloggers report some tubs are warmed in winter. There's an hinoki open-air bath renewed in 2023 and a 40°C clay 'Ataraxia' room for long, low-temperature soaks. Japanese guests rate it 4.70 across 215 reviews on one major site and 4.7 across 512 on another. The complaints: ageing buildings with thin walls, creaking corridors and a musty smell in places, stink bugs in spring and autumn, baths small for the inn's size with no private bath, simple rather than lavish food, minimal amenities and a few service slips. Official rates run about ¥26,400–33,000 per person with two meals.