Kuronagi Onsen Ryokan (Day Use)

Spring-source temperature

90°C or higher at the spring, according to the current inn page; an older technical article gives about 97°C

Bathing temperature

Not published

Spring source

Three sources near the large outdoor bath at Kuronagi Onsen

Spring classification

Weakly alkaline simple spring (low-tonicity, high-temperature spring)

pH

Not published; the inn describes the spring as weakly alkaline

Flow rate

About 2,000 L/min for the source beside the inn

Water handling

The mixed large outdoor bath and women's Tenjo-no-Yu outdoor bath use hot spring water with added water to bring down the temperature. The separate men's and women's indoor baths use a heat exchanger to cool the water and are described as 100% spring water without added water; the taps and showers also use spring water. Outdoor bathing may be restricted or rescheduled because of weather, high water or cleaning.

The 2026 operating season is May 1 through the morning of November 24; October 7 is listed as a closure date. Reception is 09:00–15:15, adults ¥1,100, children ¥500 and preschoolers free. The station-to-inn trail takes about 20–30 minutes. Tattoos are unconfirmed; clothing allowed in the mixed bath does not settle that policy.