Shiroyu — the signature 'white bath' source of the Tsuru-no-yu lineage. A sulfur-bearing sodium-calcium chloride-bicarbonate spring (hydrogen-sulfide sub-type), emerging at 55.7 degC and delivered to the tubs at about 42 degC. The water is milky white from suspended sulfur with the unmistakable rotten-egg note of H2S, and beneath that the salt-tinged warmth of chloride is softened by bicarbonate. One of the iconic turbid baths of the Tohoku region.
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
Warming
Salt forms a film on the skin that slows heat loss, so the warmth lingers long after the bath (the classic heat-keeping water, netto 熱の湯).
cold sensitivity
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
The analysis date is not recorded on our copy of the certificate.
- Active stage of any illness (especially with fever), active tuberculosis, advanced malignant tumor, or severe cardiopulmonary insufficiency from serious heart or lung disease, kidney disease with edema, gastrointestinal bleeding, visible bleeding, acute exacerbation of a chronic illness
Measured at the source
On the certificate
The analysis date is not recorded on our copy of the certificate.
- Chronic muscle or joint pain or stiffness, rheumatoid arthritis, osteoarthritis, lower back pain, neuralgia, frozen shoulder, bruises, sprains and the like (chronic phase), muscle stiffness associated with motor paralysis, cold sensitivity, peripheral circulation disorders, reduced gastrointestinal function, mild hypertension, impaired glucose tolerance (diabetes), mild hypercholesterolemia, mild asthma or emphysema, hemorrhoid pain, autonomic nervous system instability, stress-related symptoms (sleep disorders, depressed mood), convalescence, fatigue recovery, general health improvement
- Cuts, peripheral circulation disorders, cold sensitivity, depressed mood, dry skin, atopic dermatitis, psoriasis vulgaris, chronic eczema, pyoderma
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.
- Kario K et al. Hemodynamic Effects of Hot Spring Bathing. Hypertension Research 46(3):711–720, 2023.
- 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