An alkaline simple thermal spring, drawn as a blend of the Kinugawa-Kawaji Kanko Kaihatsu No. 1 and 2 wells with the Oharazawa municipal source. Lightly mineralized and gentle on the body, it takes its character from alkalinity rather than mineral load: the water has the slippery, soft-skinned feel of Japan's beauty-water family. The composition notice posted in the building lists it for neuralgia, muscle and joint pain, joint stiffness, cold sensitivity and fatigue recovery. The baths run undiluted, but are reheated to a comfortable bathing temperature and, for hygiene, recirculated through a filter and treated with a chlorine-based disinfectant.
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 with fever)
- Active tuberculosis
- Malignant tumor
- Severe heart disease
- Respiratory failure
- Renal failure
- Bleeding disorders
- Severe anemia
- Any other actively progressing illness
- Pregnancy (especially 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.
- Calciumsettling and calming; can leave a white mineral bloomCa²⁺75.7mgP66 national70%
- Sodiumsalt's cation — pairs with chloride to make the water saltyNa⁺37.3mgP8 national30%
- MagnesiumMg²⁺0.10mgP11 national0.2%
- AluminumAl³⁺0.0000mg0.0%
- Iron (II)Fe²⁺0.0000mg0.0%
- Iron (III)Fe³⁺0.0000mg0.0%
- HydrogenH⁺0.0000mg0.0%
- PotassiumK⁺0.0000mg0.0%
- LithiumLi⁺0.0000mg0.0%
- ManganeseMn²⁺0.0000mg0.0%
- AmmoniumNH₄⁺0.0000mg0.0%
- Sulfate"gypsum / Glauber's salt" — vessels and wound healingSO₄²⁻196mgP64 national73%
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻37.6mgP23 national19%
- Carbonatestrongly alkaline; slippery feelCO₃²⁻6.0mgP37 national4%
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻9.8mgP6 national3%
- Fluoridetrace; drinking limits applyF⁻1.5mgP54 national1%
- BO2BO₂⁻0.0000mg0.0%
- BromideBr⁻0.0000mg0.0%
- Hydrogen sulfideHS⁻0.0000mg0.0%
- HSiO3HSiO₃⁻0.0000mg0.0%
- HSO4HSO40.0000mg0.0%
- NitriteNO₂⁻0.0000mg0.0%
- NitrateNO₃⁻0.0000mg0.0%
- HydroxideOH⁻0.0000mg0.0%
- SS²⁻0.0000mg0.0%
- Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃31.1mgP13 national
- Metaboric acidmetaboric acid — mildly antibacterialHBO₂1.2mgP13 national
- Metaarsenious acidHAsO₂0.0000mg
- Free carbon dioxidefizz — widens blood vessels (strong above 1000 mg/kg)CO₂0.0000mg
- Free hydrogen sulfide"egg" smell — opens vessels, antibacterialH₂S0.0000mg
- ArsenicAs0.02mgP33 national
- CopperCu< —mg
- Mercurytoxic trace — part of the drinking-safety checkHg< —mg
- LeadPb< —mg
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.