Kobo-no-Yu Nagaoka (Day Use)

Spring-source temperature

Not published

Bathing temperature

38.5–40°C for the medicinal-stone radon bath; this is a bath temperature, not a source temperature

Spring source

Three springs within the facility; individual source names and current analysis values are not published on the main pages

Spring classification

Natural hot spring. The facility markets it as a medicinal-stone radon bath, but does not publish a formal classification for the source itself on its current main pages.

pH

Not published

Flow rate

Not published; the facility describes the three springs as abundant

Water handling

The facility says water flowing from the onsen outlets is free-flowing and not recirculated. Hokutolite is placed beneath the outlets, while Hokutolite and Baden-Baden stone are used in the stone-bed and mist-sauna areas. These materials do not establish that the source itself is legally classified as a radioactive spring. Water addition, heating and disinfection conditions are not fully published.

Tattoos are not permitted. Day use runs 06:00–23:00, last admission 22:00. Adult prices vary by entry time and day: ¥1,900/¥2,200 for 06:00–16:00, ¥1,400/¥1,500 for 16:00–22:00 on weekdays/weekends and public holidays, and ¥2,800 during special periods. A private sauna is a separate paid option.