A lone day-bath building among the fields on the outskirts of Nirasaki, north-west of the Kōfu basin, and a nationally known pilgrimage spot for onsen lovers. Nothing is added or altered – no dilution, heating, recirculation or chlorine – and as you settle into the tepid 38°C sodium chloride-bicarbonate spring, your whole body is coated in fine bubbles, said to be among the most abundant in Japan. The faintly greenish-yellow water carries a whisper of sulfur and iron, and the source running from a tap in the bathroom can be drunk (fizzy, iron-tinged). There is no open-air bath or sauna – just one big indoor pool and washing stations, like a sentō – but the windows frame the Yatsugatake and Kayagatake peaks, and the mild water makes an hour disappear. Adults pay ¥600, children ¥300, soap and shampoo provided. Open 10:00–20:00, closed Tuesdays (next day if a holiday) and Fridays, with free parking for 25 cars. About 10 minutes by taxi from Nirasaki Station on the JR Chūō Line or 15 minutes from Nirasaki IC on the Chūō Expressway.

✔ Verified operating: 2026-09 ゆる〜と／じゃらん（大人600円 小人300円・10–20時・火（祝日翌日）・金曜休・駐車25台・純かけ流し 38.2℃ pH7.9）

Prices and hours change. Check official sources before visiting.

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