A strongly alkaline simple sulfur spring (pH 10.1 at the wellhead) — the pronounced slipperiness of an alkaline 'beauty-water' family member, with just enough hydrogen sulfide to register on the certificate. Total mineralization is light (243 mg/kg) and the source emerges at 27.3 °C, so the water is a cold-mineral spring reheated for bathing. Wellhead color is faintly brown and slightly turbid with a mild earthy note.
Good for
Skin conditions
Sulfur and acidic waters are antibacterial and keratolytic, studied for atopic dermatitis and psoriasis.
atopic skin, eczema
Circulation
Skin-absorbed CO₂ and hydrogen sulfide relax the vessel walls; carbon-dioxide springs can raise peripheral blood flow several-fold.
tired legs
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
Cuts
Mineral-rich chloride, sulfate and sulfur waters have a long-recorded soothing effect on minor cuts and slow-healing skin.
minor wounds
Recovery
Warmth and buoyancy lower stress markers and improve sleep; habitual bathing is linked to lower rates of depression.
fatigue, stress
Take care
Sensitive-skin caution
Strongly acidic or sulfur-rich water can sting broken, atopic-flare, or dry elderly skin. Ease in slowly and rinse off if it stings.
broken or dry skin
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⁺50.1mgP14 national65%
- Aluminumshows up in acidic volcanic waterAl³⁺6.4mgP85 national21%
- Magnesiummild; a laxative if you drink itMg²⁺1.3mgP28 national3%
- Iron (II)rusts brown in air; iron for anemia when drinkableFe²⁺2.4mgP74 national3%
- Potassiumminor; matters for drinking limitsK⁺1.6mgP19 national1%
- HSiO3HSiO₃⁻84.5mgP100 national39%
- Carbonatestrongly alkaline; slippery feelCO₃²⁻24.8mgP76 national25%
- Sulfate"gypsum / Glauber's salt" — vessels and wound healingSO₄²⁻24.8mgP33 national15%
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻26.0mgP16 national13%
- Fluoridetrace; drinking limits applyF⁻4.3mgP74 national7%
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻7.5mgP11 national6%
- HydroxideOH⁻2.0mgP95 national4%
- Hydrogen sulfidesulfur character — antibacterialHS⁻2.4mgP81 national2%
- Free carbon dioxidefizz — widens blood vessels (strong above 1000 mg/kg)CO₂0.0000mg
- Free hydrogen sulfide"egg" smell — opens vessels, antibacterialH₂S0.0000mg
- CadmiumCdNDmg
- ChromiumCr< —mg
- Mercurytoxic trace — part of the drinking-safety checkHg< —mg
- LeadPbNDmg
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.
- Tei C, Kihara T. Waon Therapy for Chronic Heart Failure. J. Cardiology 53(2):214–218, 2009.
- Coavoy-Sánchez SA et al. Hydrogen sulfide and dermatological diseases. Int. J. Dermatology, 2019.
- Naito Y et al. A Hot-Spring Water Improves Inflammatory Conditions in an Atopic Dermatitis Model. Biomedicines 13(11):2707, 2025.
- Akiyama H et al. Antimicrobial effects of acidic hot-spring water on S. aureus. J. Dermatological Science 24(3):193–200, 2000.
- Toriyama T et al. Carbon dioxide foot bathing on critical limb ischemia. International Angiology 21(4):367–373, 2002.
- 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.
- Ministry of the Environment, Japan. 禁忌症及び入浴又は飲用上の注意事項 (2014 notice).official