Nasu Onsen Sanraku

A 1923 inn whose own spring is piped 5.4 km from beside the Imperial Villa's source and never heated or recirculated, with a forest-ringed open-air bath of about 30 tatami and well-loved kaiseki — but 2026 reviews flag scalding in-room tubs, ageing fittings, empty lounge bottles and thin staffing

Sanraku opened in 1923, when its founder piped water 5.4 km from springs in the Ōmaru valley — next to the Nasu Imperial Villa's own source — down to this site on the Nasu slope. The inn says the then Crown Prince, later Emperor Shōwa, liked its view over the Nasunogahara plain so much that the villa was planned in Nasu, and Yosano Akiko wrote poems here. Now run by the Ken Hotels group, it has 39 rooms in three wings. The draw is the water: a neutral simple spring mixed from 16 sources, gravity-fed at about 800 litres a minute and, the inn says, never heated, recirculated or filtered — in the large and small open-air baths under the maples and in the rooms with private baths. Japanese guests rate it 4.67 across 389 reviews on one major site (dinner 4.71, baths 4.70), 4.6 across 422 on another and 4.33 across 91 on a third, where baths score 4.62 but facilities only 4.09. Bloggers from 2024 to 2026 praise the 'pond-like' outdoor bath, a nakai assigned to each room, kaiseki that one March 2025 visitor called the best food of any inn that year, and free sake and wine in the lounge from 16:00 to 18:00. The catches, mostly dated 2025–2026: a big house that can feel crowded in the lounge and corridors, lounge bottles left empty, in-room tubs too hot to use without adding water (scald-level in one September 2026 review), worn fittings and sticking bath doors, slips such as breakfast rice not yet cooked, thin staffing, no vending machines, and a stay of about ¥200,000 for two that one August 2026 guest found poor value. Two-meal rates start around ¥53,600–65,300 for two in a standard room; rooms with private baths cost much more.