Kunshi no Yu
Analysis UnverifiedCounted among Kusatsu's historic "Twelve Baths" since the Edo period, Kunshi no Yu is said to have been named in the Kan'ei era and still bubbles up west of the Yubatake, toward Sainokawara. Flowing naturally at 64.7 liters per minute, its clear water carries drifting white mineral flakes and a gentle sulfur aroma that distills the essence of Kusatsu.
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.
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.
The aroma typical of sulfur springs, with circulatory and antibacterial effects.
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.
▸Note
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.
At pH 2.2 the water is strongly acidic, so start with short soaks of about five minutes and rest between dips. Its comfortable 42°C temperature tempts long baths; step out if your skin tingles, and sensitive skin may benefit from a fresh-water rinse.
With a pH of 2.2 and 2.5 mg/kg of free hydrogen sulfide, Kunshi no Yu has long supported Kusatsu's healing tradition and is associated with balneotherapy that may support immune system stimulation. Its 183 mg/kg of metasilicic acid also leaves a silky skin feel after bathing, ideal for washing away everyday fatigue.
Strongly acidic at pH 2.2, the water can irritate skin and mucous membranes. Keep it out of your eyes, and bathe briefly if your skin is sensitive or dry.
※ See the analysis data below for detailed contraindications
ANALYSIS DATAView all analysis fields ▼
Source Info
- Source name
- Kunshi no Yu
- Spring type
- Acidic Sulfur-containing Aluminum Sulfate and Chloride Hot Spring (hydrogen sulfide type)
- Source temperature
- 42.3℃
- pH
- 2.2
- Flow rate
- 64.7 L/min
- Flow type
- 自然湧出
- Osmotic pressure
- 低張性
Analysis Document
- Analysis date
- 2016-08-04
- 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⁺
- 6.9 mg/kg
- Sodium ion Na⁺
- 46.3 mg/kg
- Potassium ion K⁺
- 22.2 mg/kg
- Magnesium ion Mg²⁺
- 34.2 mg/kg
- Calcium ion Ca²⁺
- 70.5 mg/kg
- Aluminum ion Al³⁺
- 44.7 mg/kg
- Manganese ion Mn²⁺
- 1.3 mg/kg
- Iron(II) ion Fe²⁺
- 12.3 mg/kg
- Lead ion Pb²⁺
- < 0.005 mg/kg
- Copper ion Cu²⁺
- 0.01 mg/kg
- Total cations
- 0.24 mg/kg
Anions
- Fluoride ion F⁻
- 10.1 mg/kg
- Chloride ion Cl⁻
- 261 mg/kg
- Sulfate ion SO₄²⁻
- 576 mg/kg
- Hydrogen sulfate HSO₄⁻
- 134 mg/kg
- Total anions
- 0.98 mg/kg
Undissociated Components
- Sulfuric acid H₂SO₄
- 2.3 mg/kg
- Metasilicic acid H₂SiO₃
- 183 mg/kg
- Metaboric acid HBO₂
- 6.7 mg/kg
- Total undissociated
- 0.19 mg/kg
Dissolved Gas
- Free carbon dioxide CO₂
- 168 mg/kg
- Free hydrogen sulfide H₂S
- 2.5 mg/kg
- Total dissolved gas
- 0.17 mg/kg
Totals
- Total dissolved substances
- 1.4 mg/kg
- Component total
- 1.6 mg/kg
- Evaporation residue
- 1.2 mg/kg
Usage
- Heating
- No
- Dilution
- No
- Recycle / Filter
- No
- Additives
- No
- Disinfection
- No
Indications & Contraindications
- Bathing indications
- Atopic dermatitis, Plaque psoriasis, Epidermal suppuration, Impaired glucose tolerance (diabetes), Chronic eczema, Cuts and grazes, Peripheral circulatory failure, Poor circulation, Depression, Xeroderma
- General indications
- High blood pressure (mild), Rheumatoid arthritis, Autonomic instability, Insomnia, Chronic pain or stiffness in muscles and joints, Muscle stiffness due to motor paralysis, Gastrointestinal dysfunction
- Contraindications
- Acute illness (especially with fever), Active tuberculosis, Malignant tumors, Severe heart disease, Respiratory failure, Renal failure, Bleeding disorders, Severe anemia, Any actively progressing illness, Pregnancy (especially early and late stages), Sensitive skin or mucous membranes, eye conditions (acidic springs), Severe chronic dermatitis (sulphur springs)
Drinking
- Drinkability
- Not drinkable
