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, nettō 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
- 病気の活動期(特に熱のあるとき)、活動性の結核、進行した悪性腫瘍又は重篤な心臓若しくは肺の病気による高度の心肺機能不全、むくみのあるような腎臓病、消化管出血、目に見える出血があるとき、慢性の病気の急性増悪期
Measured at the source
On the certificate
- 筋肉若しくは関節の慢性的な痛み又はこわばり、関節リウマチ、変形性関節症、腰痛症、神経痛、五十肩、打撲、捻挫などの慢性期、運動麻痺における筋のこわばり、冷え性、末梢循環障害、胃腸機能の低下、軽症高血圧、耐糖能異常(糖尿病)、軽い高コレステロール血症、軽い喘息又は肺気腫、痔の痛み、自律神経不安定症、ストレスによる諸症状(睡眠障害、うつ状態など)、病後回復期、疲労回復、健康増進
- きりきず、末梢循環障害、冷え性、うつ状態、皮膚乾燥症、アトピー性皮膚炎、尋常性乾癬、慢性湿疹、表皮化膿症
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