A weakly alkaline simple thermal spring. The wellhead temperature reaches a hot 56 °C, yet the water itself is lightly mineralized and gentle on the skin — a soft, easy soak rather than a chemistry-forward one.
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
Smooth skin
Bicarbonate and alkalinity gently lift dead keratin while silica hydrates, leaving skin smooth. This is the basis of the beautifying-water (bijin-no-yu 美人の湯) reputation.
dry, rough skin
Recovery
Warmth and buoyancy lower stress markers and improve sleep; habitual bathing is linked to lower rates of depression.
fatigue, stress
Take care
- Acute illness (especially when fever is present)
- Active tuberculosis
- Malignant tumor
- Severe heart disease
- Respiratory failure
- Renal failure
- Bleeding disorders
- Severe anemia
- Any illness in an actively progressing stage
- Pregnancy (especially the early and late stages)
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⁺6.2mgP1 national
- Calciumsettling and calming; can leave a white mineral bloomCa²⁺0.40mgP1 national
- Potassiumminor; matters for drinking limitsK⁺0.20mgP1 national
- Magnesiummild; a laxative if you drink itMg²⁺0.20mgP14 national
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻26.5mgP16 national
- Fluoridetrace; drinking limits applyF⁻0.20mgP16 national
- Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃14.2mgP2 national
- Metaboric acidmetaboric acid — mildly antibacterialHBO₂0.70mgP10 national
Measured at the source
On the 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.
- Naito Y et al. A Hot-Spring Water Improves Inflammatory Conditions in an Atopic Dermatitis Model. Biomedicines 13(11):2707, 2025.
- 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.
- Li H et al. Bicarbonate Ionized Water Bathing Enhances Natural Killer Cell Activity. Scientific Reports 14:51851, 2024.
- Takeda M et al. Hot spring bathing practices have a positive effect on mental health in Japan. Heliyon 9(9):e19631, 2023.