A gentle simple thermal spring pumped from beneath Osaka's Yodogawa ward. It is lightly mineralized at 0.38 g/kg of dissolved solids, yet nearly 95% of its anions are bicarbonate, which rounds out an already weakly alkaline, soft-on-the-skin feel. Metasilicic acid at 50 mg/kg brings it to the edge of Japan's beauty-water family, and the water itself carries a faint yellow tint while staying clear, tasteless and odorless. The posted analysis lists it for cold sensitivity and peripheral circulation problems, for fatigue recovery, and for stress-related complaints including insomnia and depressed mood.
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
- Active stage of any illness (especially with fever)
- Active tuberculosis
- Marked physical debilitation, such as advanced malignant tumor or severe anemia
- Severe heart or lung disease causing breathlessness on slight exertion
- Severe kidney disease accompanied by edema
- Gastrointestinal bleeding
- Any visible bleeding
- Acute exacerbation of a chronic illness
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⁺59.3mgP17 national65%
- Calciumsettling and calming; can leave a white mineral bloomCa²⁺14.3mgP31 national18%
- Magnesiummild; a laxative if you drink itMg²⁺5.4mgP52 national11%
- AmmoniumNH₄⁺2.3mgP82 national3%
- Potassiumminor; matters for drinking limitsK⁺2.5mgP25 national2%
- Iron (II)Fe²⁺0.70mgP58 national0.6%
- ManganeseMn²⁺0.30mgP53 national0.3%
- StrontiumSr²⁺0.10mgP26 national0.1%
- Aluminumshows up in acidic volcanic waterAl³⁺< —mg
- BariumBa²⁺< —mg
- Iron (III)Fe³⁺< —mg
- Hydrogenmakes the water acidic — sharp and bactericidalH⁺< —mg
- LithiumLi⁺< —mg
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻238mgP60 national95%
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻7.3mgP10 national5%
- Bromidetrace, sea-originBr⁻< —mg
- Carbonatestrongly alkaline; slippery feelCO₃²⁻< —mg
- Fluoridetrace; drinking limits applyF⁻< —mg
- Hydrogen phosphateHPO₄²⁻< —mg
- Hydrogen sulfidesulfur character — antibacterialHS⁻< —mg
- Iodideyellows in air; helps blood lipidsI⁻< —mg
- NitrateNO₃⁻< —mg
- Thiosulfateoxidized sulfurS₂O₃²⁻< —mg
- Sulfate"gypsum / Glauber's salt" — vessels and wound healingSO₄²⁻< —mg
- Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃50.3mgP29 national
- Metaarsenious acidHAsO₂< —mg
- Metaboric acidmetaboric acid — mildly antibacterialHBO₂< —mg
- Free carbon dioxidefizz — widens blood vessels (strong above 1000 mg/kg)CO₂4.0mgP27 national
- Free hydrogen sulfide"egg" smell — opens vessels, antibacterialH₂S< —mg
Measured at the source
On the certificate
- Chronic muscle or joint pain and stiffness (rheumatoid arthritis, osteoarthritis, lower back pain, neuralgia, frozen shoulder, bruises, sprains — chronic phase)
- Muscle stiffness associated with motor paralysis
- Cold sensitivity
- Peripheral circulation disorders
- Reduced gastrointestinal function
- Mild hypertension
- Diabetes
- Mild hypercholesterolemia
- Mild asthma or emphysema
- Hemorrhoid pain
- Stress-related symptoms
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.