Waka-no-Yu Spring
Analysis UnverifiedKusatsu Onsen has long been celebrated as a premier "medicinal spring" across Japan, drawing pilgrims from across the nation during the Edo period to seek therapeutic bathing. Wakanoyou stands as one of its naturally gushing sources, keeping alive the healing traditions of Kusatsu's thermal culture. It holds particular promise for those battling chronic skin conditions or poor circulation, and those seeking a profound reset from daily stress.
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.
A natural moisturizer also used in skincare lotions. Forms a thin veil on the skin to reduce moisture loss after bathing.
Mild antibacterial action keeps the skin clean. Trace transdermal absorption supports tooth and bone health.
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 its potent acidity—pH 2.0—newcomers should begin with brief 3-5 minute soaks, carefully observing skin response before gradually extending time. After bathing, tradition calls for patting dry without rinsing away the mineral essence; however, those with sensitive skin should opt for a gentle lukewarm rinse. Bathe once or twice daily, hydrating generously with a full cup of water both before and after immersion.
The 50.5°C waters of this powerfully acidic spring—pH 2.0—deliver sulfate ions (701 mg), chloride ions (327 mg), and metasilicic acid (234 mg) that gently refine skin texture and show remarkable efficacy against stubborn conditions: atopic dermatitis, psoriasis, and chronic eczema. The hydrogen sulfide compounds further enhance peripheral circulation, addressing cold sensitivity, fatigue, and melancholic states through profound systemic renewal.
Those with sensitive skin, delicate mucous membranes, or age-related xerosis should refrain from bathing. Due to the strong acidity, rinse thoroughly in warm water post-bath, monitor closely for thermal illness (onset 3 days–1 week), and start conservatively with short, infrequent soaks.
※ See the analysis data below for detailed contraindications
ANALYSIS DATAView all analysis fields ▼
Source Info
- Source name
- 若の湯
- 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）（低張性酸性高温泉）
- Source temperature
- 50.5℃
- pH
- 2
- Flow type
- 自然湧出
- Osmotic pressure
- 低張性
Analysis Document
- Analysis date
- 2019-12-02
- 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⁺
- 10.2 mg/kg
- Sodium ion Na⁺
- 56.1 mg/kg
- Potassium ion K⁺
- 26.9 mg/kg
- Magnesium ion Mg²⁺
- 35.4 mg/kg
- Calcium ion Ca²⁺
- 73.9 mg/kg
- Aluminum ion Al³⁺
- 49.4 mg/kg
- Manganese ion Mn²⁺
- 1.8 mg/kg
- Iron(II) ion Fe²⁺
- 18.8 mg/kg
- Total cations
- 0.27 mg/kg
Anions
- Fluoride ion F⁻
- 9.3 mg/kg
- Chloride ion Cl⁻
- 327 mg/kg
- Sulfate ion SO₄²⁻
- 701 mg/kg
- Hydrogen sulfate HSO₄⁻
- 242 mg/kg
- Total anions
- 1.3 mg/kg
Undissociated Components
- Metasilicic acid H₂SiO₃
- 234 mg/kg
- Metaboric acid HBO₂
- 7.9 mg/kg
- Total undissociated
- 0.25 mg/kg
Dissolved Gas
- Free carbon dioxide CO₂
- 110 mg/kg
- Free hydrogen sulfide H₂S
- 6.0 mg/kg
- Total dissolved gas
- 0.12 mg/kg
Totals
- Total dissolved substances
- 1.8 mg/kg
- Component total
- 1.9 mg/kg
- Evaporation residue
- 1.8 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, contusions, sprains and other chronic stages), muscle stiffness due to motor paralysis, gastrointestinal dysfunction (stomach heaviness, intestinal gas buildup, etc.), high blood pressure (mild), dyslipidemia (mild), mild asthma or emphysema, hemorrhoids pain, autonomic instability, stress-related symptoms (sleep disorders, etc.), post-illness recovery period, fatigue recovery, health promotion. Atopic dermatitis, psoriasis vulgaris, impaired glucose tolerance (diabetes), pyogenic infections of the epidermis, chronic eczema, cuts and grazes, peripheral circulatory failure, poor circulation, depression, xeroderma.
- Contraindications
- Active disease phase (particularly when fever is present), active tuberculosis, advanced malignant tumors or severe cases of physical weakness such as marked anemia, severe heart or lung disease causing breathlessness with minimal activity, severe kidney disease with edema, gastrointestinal hemorrhage, visible bleeding, acute exacerbation of chronic diseases. People with sensitive skin or mucous membranes, xeroderma in elderly patients.
Drinking
- Drinkability
- Not drinkable