A simple thermal spring that emerges at 98.1 °C — among Japan's hottest natural sources. The water itself is very lightly mineralized, at just 99 mg/kg of dissolved solids, and close to neutral at pH 6.5, so it is gentle on the body rather than assertive. Because the wellhead runs so hot, the posted notice states the bath is diluted with water, reaching the bathing point at around 53 °C. The panel lists the water for neuralgia, muscle and joint pain, cold sensitivity and fatigue recovery, and flags that drinking is not permitted without a separate license.
Good for
Aches & joints
Warmth eases stiffness and raises the pain threshold. Radon and sulfate springs show the strongest evidence for joint and muscle pain.
stiff shoulders
Recovery
Warmth and buoyancy lower stress markers and improve sleep; habitual bathing is linked to lower rates of depression.
fatigue, stress
Take care
From a certificate analyzed in 2003.
This list uses the wording the Ministry of the Environment replaced in 2014, so it may not match a current certificate. Items marked † were removed from the official list of contraindications then, or include a condition that was. If you have a health condition, ask a doctor before bathing.
- Acute illness (especially with fever)
- Active tuberculosis
- Malignant tumor
- Severe heart disease
- Respiratory failure
- Renal failure
- Bleeding disorders
- Severe anemia
- Any other illness in an actively progressing stage
- Pregnancy (especially the early and late stages) (dropped from the official list in 2014)
Full composition
The bar is each ion's share of charge (mval%) within its group; over 20% names the spring. Gases, silica and trace metals are measured by mass only.
- Sodiumsalt's cation — pairs with chloride to make the water saltyNa⁺14.7mgP3 national65%
- Calciumsettling and calming; can leave a white mineral bloomCa²⁺3.5mgP13 national18%
- AmmoniumNH₄⁺1.5mgP74 national8%
- Potassiumminor; matters for drinking limitsK⁺2.1mgP22 national5%
- Magnesiummild; a laxative if you drink itMg²⁺0.50mgP20 national4%
- Iron (II)Fe²⁺0.10mgP29 national0.0%
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻16.0mgP15 national43%
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻24.0mgP15 national37%
- Sulfate"gypsum / Glauber's salt" — vessels and wound healingSO₄²⁻10.0mgP21 national20%
- Metaboric acidmetaboric acid — mildly antibacterialHBO₂25.9mgP78 national
- Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃0.90mgP1 national
- Free carbon dioxidefizz — widens blood vessels (strong above 1000 mg/kg)CO₂14.1mgP45 national
Measured at the source
On the certificate
From a certificate analyzed in 2003.
This list uses the wording the Ministry of the Environment replaced in 2014, so it may not match a current certificate.
- Chronic digestive disorders
- Hemorrhoids
- Cold sensitivity
Evidence
- Maeda M. 温泉の医学的効果とその科学的根拠. J. Hot Spring Science 70:197–207, 2021.
- Donaubauer AJ et al. Serial radon spa therapy on pain in musculoskeletal disorders. Frontiers in Immunology, 2024.
- Verhagen AP et al. Balneotherapy for rheumatoid arthritis. Cochrane Database of Systematic Reviews CD000518, 2015.
- Takeda M et al. Hot spring bathing practices have a positive effect on mental health in Japan. Heliyon 9(9):e19631, 2023.