Mukaitaki

Japan's first registered-heritage inn: a former Aizu clan bath retreat with scalding free-flowing water, free private baths and carp dinners in your room — and a lot of stairs

Mukaitaki began as 'Kitsune-yu', a bath retreat of the Aizu domain, and has been run by the Hirata family as an inn since 1873. In 1996 it became the first property registered under Japan's new tangible cultural property system — the entrance, the detached Hanare and two guest wings — and its garden is registered too; a prince once asked that it never be rebuilt in concrete. Japanese guests adore it: a perfect 5.0 across 355 reviews on one major site, with 5.0 for both baths and cleanliness, and 4.89 for service on another. The water is the draw: every bath is 100% free-flowing from the inn's own naturally rising spring, with no heating, added water or recirculation. Kitsune-yu is famously hot (44–45°C) with no taps; Saru-no-yu is gentler, and three private baths are free with no booking. Dinner and breakfast come to your room, built on Aizu staples — sweet-simmered carp, kozuyu soup, herring pickled with sansho — with no shrimp, crab or tuna. The complaints: stairs everywhere and no barrier-free access, a 10:00 check-out, no non-smoking rooms reported, no in-room fridge or dryer in some rooms, trainee staff, pricey drinks, homely food for some, and stink bugs in winter. Official rates start around ¥27,850 per person with two meals.