Hosen-no-yu
Analysis VerifiedEven within Kusatsu Onsen, one of Japan's three great hot springs, this is a private source available only at a specific inn. The Hosen-no-yu spring is said to have been naturally gushing from fissures in the bedrock for some 1,200 years. Unlike Kusatsu's main shared sources like Yubatake or Bandai, its waters are a rarity that can only be experienced in a very limited setting.
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.
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.
With a highly acidic pH of 2.0, those with sensitive skin and the elderly should be cautious of "yu-atari" (onsen sickness). Start with short dips to acclimate your body. The water will sting eyes and open wounds, so be careful when splashing or pouring water.
Known for its powerful sterilizing effects, this spring has a potent acidity of pH 2.0. Furthermore, it contains 208 mg/kg of metasilicic acid, said to promote skin metabolism and beautifying effects. It has been used for therapeutic bathing by those with skin concerns like atopic dermatitis and chronic eczema.
Avoid bathing during active phases of illness or if you are extremely weak. Due to the strong acidity, individuals with sensitive skin, mucous membranes, or xeroderma (dry skin) in the elderly should be particularly cautious.
※ See the analysis data below for detailed contraindications
Kusatsuonsen Tenojiya
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ANALYSIS DATAView all analysis fields ▼
Source Info
- Source name
- 宝泉の湯
- 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）
- Source temperature
- 45℃
- pH
- 2
- Flow rate
- 72.2 L/min
- Flow type
- 自然湧出
- Osmotic pressure
- 低張性
Analysis Document
- Analysis date
- 2015-05-21
- 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)
Cations
- Hydrogen ion H⁺
- 9.8 mg/kg
- Sodium ion Na⁺
- 46.4 mg/kg
- Potassium ion K⁺
- 24.4 mg/kg
- Magnesium ion Mg²⁺
- 33.1 mg/kg
- Calcium ion Ca²⁺
- 69.9 mg/kg
- Aluminum ion Al³⁺
- 43.3 mg/kg
- Manganese ion Mn²⁺
- 1.7 mg/kg
- Iron(II) ion Fe²⁺
- 15.2 mg/kg
- Total cations
- 0.24 mg/kg
Anions
- Fluoride ion F⁻
- 8.4 mg/kg
- Chloride ion Cl⁻
- 274 mg/kg
- Sulfate ion SO₄²⁻
- 596 mg/kg
- Hydrogen sulfate HSO₄⁻
- 196 mg/kg
- Total anions
- 1.1 mg/kg
Undissociated Components
- Sulfuric acid H₂SO₄
- 4.8 mg/kg
- Metasilicic acid H₂SiO₃
- 208 mg/kg
- Metaboric acid HBO₂
- 7.3 mg/kg
- Total undissociated
- 0.22 mg/kg
Dissolved Gas
- Free carbon dioxide CO₂
- 96.8 mg/kg
- Free hydrogen sulfide H₂S
- 6.6 mg/kg
- Total dissolved gas
- 0.10 mg/kg
Totals
- Total dissolved substances
- 1.5 mg/kg
- Component total
- 1.6 mg/kg
- Evaporation residue
- 1.4 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 (chronic phase of rheumatoid arthritis, osteoarthritis, low back pain, neuralgia, frozen shoulder, bruises, sprains), Muscle stiffness due to motor paralysis, Gastrointestinal dysfunction (stomach sluggishness, intestinal gas), High blood pressure (mild), Dyslipidemia, Mild asthma or emphysema, Hemorrhoid pain, Autonomic instability, Symptoms caused by stress (insomnia, etc.), Post-illness recovery, Fatigue recovery, Health promotion, Atopic dermatitis, Psoriasis vulgaris, Impaired glucose tolerance (diabetes), Pyoderma, Chronic eczema, Cuts and grazes, Peripheral circulatory failure, Poor circulation, Depression, Xeroderma
- Contraindications
- Active phases of illness (especially with fever), active tuberculosis, advanced malignant tumors or severe anemia with significant physical decline, severe heart or lung disease causing shortness of breath with slight movement, severe kidney disease with swelling, gastrointestinal bleeding, visible bleeding, acute exacerbation of chronic illness, individuals with sensitive skin or mucous membranes, xeroderma (dry skin) in the elderly.
Drinking
- Drinkability
- Not drinkable