Yubatake Spring
Analysis UnverifiedKusatsu's iconic Yubatake field has drawn literati, samurai, and commoners since the Edo period as one of Japan's most celebrated thermal springs. The white thermal mist and sulfurous hydrogen aroma drifting across the Yubatake landscape remain unchanged, inviting every visitor into an extraordinary experience. This legendary source is especially recommended for those battling skin irritation and chronic dermatological troubles, seekers of respite from daily stress, and dedicated onsen enthusiasts in pursuit of authentic Japanese thermal bathing.
The bar length shows how abundant each component is compared to thresholds that make it "distinctive" (therapeutic spring standards, beauty spring criteria, etc.).
Strong astringent action that tightens skin. A key component of acidic springs, suited to oily or acne-prone skin.
The source of the distinctive sulfur smell. Dilates blood vessels via skin and inhalation to strongly boost circulation.
Mild antibacterial action keeps the skin clean. Trace transdermal absorption supports tooth and bone health.
A natural moisturizer also used in skincare lotions. Forms a thin veil on the skin to reduce moisture loss after bathing.
A trace component with gentle antibacterial and anti-inflammatory action.
Scores are calculated from mineral analysis data based on the Mineral Spring Analysis Guidelines (Ministry of Environment, Japan). They are unrelated to facility atmosphere or service quality.
The temperature, pH and component values shown here are based on the hot spring analysis (source). Actual values in the bath may differ depending on heating, dilution, recycling and filtration. Please check current usage status at the facility.
Given the strong acidity (pH 2.02), limit your first immersion to 3–5 minutes while monitoring your skin's response before gradually extending duration. The traditional practice is to pat dry with a towel without rinsing away thermal minerals; however, those with sensitive skin may gently rinse with warm water to reduce irritation. Begin with one to two daily immersions, progressively increasing to two or three as your body acclimates—this is the Kusatsu way.
At 52.3°C and pH 2.02, the potent acidity tightens skin surface while free hydrogen sulfide (6.2 mg/kg) delivers antimicrobial and anti-inflammatory benefits, offering scientific grounding for treating atopic dermatitis, psoriasis, and chronic eczema. Those managing glucose intolerance, peripheral circulatory disorders, and cold sensitivity find measurable improvement. Rich in sulfate ions (674.4 mg/kg), this water is widely utilized for alleviating chronic joint and muscle tension.
Those with hypersensitive skin and mucous membranes, and elderly individuals prone to xerosis, should avoid this spring. Those with active disease, severe cardiopulmonary or renal conditions, or active bleeding should refrain from bathing. Due to strong acidity, those with delicate skin should rinse gently in warm water after bathing.
※ See the analysis data below for detailed contraindications
ANALYSIS DATAView all analysis fields ▼
Source Info
- Source name
- 湯畑
- Spring type
- 酸性・含硫黄-アルミニウム-硫酸塩・塩化物温泉（硫化水素型）（低張性酸性高温泉）
- Source temperature
- 52.3℃
- pH
- 2.02
- Flow type
- 自然湧出
- Osmotic pressure
- 低張性
Analysis Document
- Analysis date
- 2023-08-04
- Analyst organization
- 一般社団法人 群馬県薬剤師会（環境衛生試験センター）
- Registration No.
- 群馬薬第2号
Cations
- Hydrogen ion H⁺
- 10.0 mg/kg
- Sodium ion Na⁺
- 59.7 mg/kg
- Potassium ion K⁺
- 30.0 mg/kg
- Ammonium ion NH₄⁺
- 0.50 mg/kg
- Magnesium ion Mg²⁺
- 39.4 mg/kg
- Calcium ion Ca²⁺
- 73.1 mg/kg
- Aluminum ion Al³⁺
- 49.1 mg/kg
- Manganese ion Mn²⁺
- 2.0 mg/kg
- Iron(II) ion Fe²⁺
- 17.8 mg/kg
- Total cations
- 0.28 mg/kg
Anions
- Fluoride ion F⁻
- 10.1 mg/kg
- Chloride ion Cl⁻
- 329 mg/kg
- Sulfate ion SO₄²⁻
- 674 mg/kg
- Hydrogen sulfate HSO₄⁻
- 227 mg/kg
- Total anions
- 1.2 mg/kg
Undissociated Components
- Metasilicic acid H₂SiO₃
- 243 mg/kg
- Metaboric acid HBO₂
- 9.8 mg/kg
- Total undissociated
- 0.26 mg/kg
Dissolved Gas
- Free carbon dioxide CO₂
- 46.9 mg/kg
- Free hydrogen sulfide H₂S
- 6.2 mg/kg
- Total dissolved gas
- 0.05 mg/kg
Totals
- Total dissolved substances
- 1.8 mg/kg
- Component total
- 1.8 mg/kg
- Evaporation residue
- 1.6 mg/kg
Usage
- Heating
- No
- Dilution
- No
- Recycle / Filter
- No
- Additives
- No
- Disinfection
- No
Indications & Contraindications
- Bathing indications
- Chronic pain or stiffness in muscles and joints (rheumatoid arthritis, osteoarthritis, low back pain, neuralgia, frozen shoulder, contusion, sprain and other chronic conditions), Muscle stiffness due to motor paralysis, Gastrointestinal dysfunction (gastric discomfort, intestinal gas accumulation, etc.), High blood pressure (mild), Dyslipidemia (mild), Mild asthma or emphysema, Hemorrhoids pain, Autonomic instability, Various symptoms caused by stress (sleep disorders, etc.), Post-illness recovery period, Fatigue recovery, Health promotion, Atopic dermatitis, Psoriasis vulgaris, Impaired glucose tolerance (diabetes), Superficial pyogenic infections, Chronic eczema, Cuts and grazes, Peripheral circulatory failure, Poor circulation, Depression, Xeroderma
- Contraindications
- Active phase of disease (especially when fever is present), Active tuberculosis, Advanced malignancy or severe cases of significant physical weakness such as severe anemia, Severe heart or lung disease that causes dyspnea with minimal exertion, Severe kidney disease with edema, Gastrointestinal bleeding, Visible bleeding, Acute exacerbation of chronic disease, Persons with sensitive skin or mucous membranes, Xeroderma in elderly persons
Drinking
- Drinkability
- Not drinkable