Oku-Yumoto, Hakone, Kanagawa Prefecture
Tenzan at Tenzan Toji-kyo
For visitors willing to travel a little farther from Hakone-Yumoto for the volume of the springs, water cooled without dilution, nightly bath changes and a quieter setting. The focus is on the water itself, not station convenience or private family baths.
Check before bathing
- Opening hours
- 09:00–23:00; last admission 22:00. There is generally no regular closing day, but the facility closes for about five days in mid-December.
- Tattoo policy
- A solo guest is not refused solely for having a tattoo, according to the current operator information. Groups with tattooed guests are not admitted. The facility also restricts groups of more than six; check its current rules before travelling.
Spring & water temperature
- Spring-source temperature
- All seven sources are hot; the hottest is about 83°C. This is the highest source temperature, not a bath temperature.
- Bathing temperature
- Not published as one fixed figure. The operator says delivery is adjusted to keep each pool within ±0.1°C of its setting.
- Spring source
- Seven nearby sources: blended sources No. 92, 93, 101, 102 and 114, plus Yumoto sources No. 74 and 115.
- Spring classification
- A mix of alkaline simple spring and sodium chloride spring; the pools vary by source.
- pH
- Varies by source. Yumoto source No. 74 is pH 9.3; that value does not represent every spring or pool.
- Flow rate
- 347 L/min combined across the seven sources (20,820 L/hour; about 500 tonnes per day).
- Water handling
- Pipelines carry water directly from the seven source locations to the baths. The operator says the high-temperature water is cooled with a heat-exchange system rather than by adding water. Flow and delivery temperature are adjusted seasonally. Every bath is drained nightly, cleaned and refilled with fresh water by morning.
- Analysis date
- 2026
Bathing indications
The facility is operated for hot-spring bathing and rest. Spring-specific indications should be checked against each source's analysis; no treatment effect is promised.
Water is piped directly from the sources. High-temperature water is cooled without dilution, and the pools are drained and refilled every day. The current overview does not give complete pool-by-pool disinfection details.
Admission is ¥1,450 for adults and ¥700 for children aged one through elementary school. Much of the facility, including admission, is cash-only. Tattooed guests may visit alone, but not as part of a group. Groups larger than six are also not accepted.
How to read a bath profile
Spring-source temperature and actual bathing temperature are kept separate. Each score is shown independently for comparison rather than collapsed into one overall score.
