Onsen OniOnsen Oni

Search Onsen Oni

Search onsen, areas, prefectures and pages.

Vira Amehata

Water profile

Vira Amehata

Spring chemistry and what it does, with the research behind it.

黄SulfurCalcium Sulfate spring · +Sulfate

A simple sulfur cold-mineral spring feeding Vira Amehata in Hayakawa-cho, deep in southern Yamanashi. The wellhead emerges below 25 °C — a cold-mineral source heated for bathing — and carries a faint yellow-brown tint with a soft rotten-egg note of H₂S and a bitter edge on the tongue. Neutral pH 7.96 and a light 0.49 g/kg of dissolved solids keep the water gentle on the body, with the sulfur character providing the personality of the bath.

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

On the 2024 certificate:Hemorrhoids

Aches & joints

Warmth eases stiffness and raises the pain threshold. Radon and sulfate springs show the strongest evidence for joint and muscle pain.

stiff shoulders

On the 2024 certificate:NeuralgiaMuscle painJoint painFrozen shoulderMotor paralysisJoint stiffnessSprainsBruises

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

On the 2024 certificate:ConvalescenceFatigue recoveryGeneral health improvement

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

Contraindications

From a certificate analyzed in 2024.

This list uses the wording the Ministry of the Environment replaced in 2014, so it may not match a current certificate. Items marked † were removed from the official list of contraindications then, or include a condition that was. If you have a health condition, ask a doctor before bathing.

  • Acute illness (especially when fever is present)
  • Active tuberculosis
  • Malignant tumor
  • Severe heart disease
  • Respiratory failure
  • Renal failure
  • Bleeding disorders
  • Severe anemia
  • Any illness in an actively progressing stage
  • Pregnancy (especially the early and late stages) (dropped from the official list in 2014)
  • Diarrhea
  • Other cases where a doctor judges drinking the spring water unsuitable

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.

Cationsshare of charge (mval%)
  • Calcium79.9mgP67 national
  • Magnesium6.5mgP57 national
  • Sodium18.0mgP4 national
  • Potassium1.5mgP17 national
  • Strontium0.70mgP75 national
  • Barium0.0000mg
  • Iron (II)0.0000mg
  • Lithium0.0000mg
  • Manganese0.0000mg
  • Ammonium0.0000mg
Anionsshare of charge (mval%)
  • Sulfate296mgP73 national
  • Bicarbonate49.4mgP30 national
  • Chloride7.5mgP10 national
  • Bromide0.0000mg
  • Carbonate0.0000mg
  • Fluoride0.0000mg
  • Hydrogen phosphate0.0000mg
  • Iodide0.0000mg
  • Nitrate0.0000mg
Non-dissociatedmeasured by mass
  • Metasilicic acid17.7mgP3 national
Trace metalsmeasured by mass
  • Cadmium< —mg
  • Copper< —mg
  • Lead< —mg

Measured at the source

Tonicity
0.49g/kg
Hypotonic
Radon
28Bq/kg
Low

On the certificate

From a certificate analyzed in 2024.

This list uses the wording the Ministry of the Environment replaced in 2014, so it may not match a current certificate.

  • Chronic digestive disorders
  • Cold sensitivity
  • Diabetes
  • Constipation

Evidence

  1. 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.
  2. Tei C, Kihara T. Waon Therapy for Chronic Heart Failure. J. Cardiology 53(2):214–218, 2009.
  3. Coavoy-Sánchez SA et al. Hydrogen sulfide and dermatological diseases. Int. J. Dermatology, 2019.
  4. Naito Y et al. A Hot-Spring Water Improves Inflammatory Conditions in an Atopic Dermatitis Model. Biomedicines 13(11):2707, 2025.
  5. Akiyama H et al. Antimicrobial effects of acidic hot-spring water on S. aureus. J. Dermatological Science 24(3):193–200, 2000.
  6. Toriyama T et al. Carbon dioxide foot bathing on critical limb ischemia. International Angiology 21(4):367–373, 2002.
  7. Donaubauer AJ et al. Serial radon spa therapy on pain in musculoskeletal disorders. Frontiers in Immunology, 2024.
  8. Verhagen AP et al. Balneotherapy for rheumatoid arthritis. Cochrane Database of Systematic Reviews CD000518, 2015.
  9. Li H et al. Bicarbonate Ionized Water Bathing Enhances Natural Killer Cell Activity. Scientific Reports 14:51851, 2024.
  10. Takeda M et al. Hot spring bathing practices have a positive effect on mental health in Japan. Heliyon 9(9):e19631, 2023.
  11. 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

Educational, not medical advice. If you have a health condition, consult a physician before onsen therapy.