Hagoromo no Yu rises on the left bank of the Kinugawa river as an alkaline simple thermal spring. Its mineral load is light and unchallenging, yet the alkalinity is pronounced enough to leave the slippery, skin-smoothing feel that places it in Japan's beauty-water family. The posted certificate lists it for neuralgia, muscle and joint pain, joint stiffness, cold sensitivity and fatigue recovery.
Good for
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 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⁺102mgP29 national
- Calciumsettling and calming; can leave a white mineral bloomCa²⁺51.4mgP57 national
- Potassiumminor; matters for drinking limitsK⁺1.9mgP21 national
- Magnesiummild; a laxative if you drink itMg²⁺0.60mgP21 national
- Iron (II)rusts brown in air; iron for anemia when drinkableFe²⁺0.10mgP29 national
- CopperCu²⁺0.0000mg
- Iron (III)Fe³⁺0.0000mg
- 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 healingSO₄²⁻203mgP64 national
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻80.9mgP34 national
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻16.1mgP11 national
- Carbonatestrongly alkaline; slippery feelCO₃²⁻6.7mgP40 national
- Fluoridetrace; drinking limits applyF⁻3.3mgP68 national
- Hydrogen sulfidesulfur character — antibacterialHS⁻0.20mgP39 national
- HydroxideOH⁻0.20mgP66 national
- AsO2AsO₂⁻0.0000mg
- BO2BO₂⁻0.0000mg
- HSiO3HSiO₃⁻0.0000mg
- HSO4HSO40.0000mg
- SS²⁻0.0000mg
- Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃48.2mgP27 national
- Metaboric acidmetaboric acid — mildly antibacterialHBO₂6.8mgP44 national
- H2SO4FreeH2SO4Free0.0000mg
- Phosphoric acidH₃PO₄0.0000mg
- Metaarsenious acidHAsO₂—mg
- Free carbon dioxidefizz — widens blood vessels (strong above 1000 mg/kg)CO₂0.0000mg
- Free hydrogen sulfide"egg" smell — opens vessels, antibacterialH₂S0.0000mg
- CadmiumCd0.0000mg
- ChromiumCr0.0000mg
- Mercurytoxic trace — part of the drinking-safety checkHg0.0000mg
- LeadPb0.0000mg
Measured at the source
On the certificate
- Neuralgia
- Muscle pain
- Joint pain
- Frozen shoulder
- Motor paralysis
- Joint stiffness
- Bruises
- Sprains
- 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.
- 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.