A blend of two wells (No.1 and No.2) registered under the Kinugawa-Kawaji Onsen Kanko Kaihatsu name, classified as an alkaline simple thermal spring. The alkalinity gives the slippery feel that puts it in Japan's beauty-water family, while the light mineralization keeps the water gentle: colorless, clear, tasteless and odorless, with nothing sharp about it. The wells sit in the Taki district of Fujihara, Shioya County.
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
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⁺31.4mgP46 national
- Sodiumsalt's cation — pairs with chloride to make the water saltyNa⁺21.6mgP4 national
- Potassiumminor; matters for drinking limitsK⁺0.80mgP11 national
- Magnesiummild; a laxative if you drink itMg²⁺0.40mgP18 national
- Aluminumshows up in acidic volcanic waterAl³⁺0.30mgP66 national
- Iron (II)rusts brown in air; iron for anemia when drinkableFe²⁺0.20mgP38 national
- CopperCu²⁺0.10mgP97 national
- Hydrogenmakes the water acidic — sharp and bactericidalH⁺0.0000mg
- Manganesetrace; companion to iron springsMn²⁺0.0000mg
- ZincZn²⁺0.0000mg
- Sulfate"gypsum / Glauber's salt" — vessels and wound healingSO₄²⁻97.3mgP53 national
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻28.4mgP18 national
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻4.3mgP6 national
- Carbonatestrongly alkaline; slippery feelCO₃²⁻3.2mgP27 national
- Fluoridetrace; drinking limits applyF⁻0.80mgP42 national
- HydroxideOH⁻0.10mgP49 national
- AsO2AsO₂⁻0.0000mg
- BO2BO₂⁻0.0000mg
- Hydrogen sulfidesulfur character — antibacterialHS⁻0.0000mg
- HSiO3HSiO₃⁻0.0000mg
- HSO4HSO40.0000mg
- SS²⁻0.0000mg
- Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃43.4mgP24 national
- H2SO4FreeH2SO4Free0.0000mg
- Metaarsenious acidHAsO₂0.0000mg
- Metaboric acidmetaboric acid — mildly antibacterialHBO₂0.0000mg
- Free carbon dioxidefizz — widens blood vessels (strong above 1000 mg/kg)CO₂0.0000mg
- Free hydrogen sulfide"egg" smell — opens vessels, antibacterialH₂S0.0000mg
- LeadPb0.05mgP84 national
- ArsenicAs0.02mgP34 national
- CadmiumCd0.0000mg
- Mercurytoxic trace — part of the drinking-safety checkHg0.0000mg
Measured at the source
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.