Ramune Onsen-kan

Wrapped in silver bubbles at 32 °C — one of Japan’s most concentrated carbonated springs

Nagayu Onsen is a quiet spa village on the Seri River at the foot of the Kuju range in Taketa, Oita, which bills itself “Japan’s No.1 carbonated spring” and has nurtured a spa-therapy culture through a sister-town tie with Bad Krozingen in Germany. Its emblem is “Ramune Onsenkan”, opened in 2005 as the annex bath of the old Daimaru Ryokan and designed by architect Fujimori Terunobu — striped walls of cedar and white plaster and a pointed roof with a pine tree growing from the top, like something from a fairy tale, drawing architecture fans as well as bathers. The outdoor baths run the 32 °C source unheated, because heating would drive off the gas; with about 1,380 mg/kg of free CO₂, among the highest in Japan, silver bubbles cling to your whole body like pearls within a minute, and although the water is tepid the boosted circulation leaves you glowing afterwards — the “ramune” (fizzy drink) bath experience. The indoor bath is a brownish, iron-tinged bicarbonate spring heated to 42 °C, and alternating between the two is the standard routine. A salty, ferrous drinking fountain stands in the courtyard, and the adjoining gallery is free for bathers. At ¥500 the outdoor baths are packed on summer weekends — go on a weekday or in winter, when 32 °C takes resolve but the place is empty.

Tips & cautions

- 32 °C outdoors feels cold at first — keep still for 5–10 minutes until the bubbles form and your body adjusts. Alternate with the 42 °C indoor bath, and finish indoors, not outdoors, so you don’t chill.

- Don’t rub your skin if you want to keep the bubbles.

- No soap or shampoo (sold) — bring your own. Mind your valuables in the lockers.

- Outdoor baths are packed on summer weekends and holidays — weekday mornings are best.

- Closed 1st Wednesday (2nd Wednesday in January and May). Private baths until 20:45.

- Sip the drinking spring sparingly (high in iron and salt).

- Tattoo policy unconfirmed — a private bath (¥2,000/hour) is the safe option.

- Also in town: Gani-yu (free mixed riverside bath), Gozen-yu (¥700) and Chosei-yu (¥300) — an easy half-day circuit.

Getting there

Ono-Taketa bus (via Kuju for Naoiri branch office) ~47 min from Bungo-Taketa Station (JR Hohi line) to “Yamawaki”, then 3 min on foot (Nagayu 7676-2, Naoiri-machi, Taketa). ~1 h by car from Oita Station, ~1 h 10 min from Kumamoto/Aso. 30 free spaces. Tel. 0974-75-2620.