1-go Otsu Sen
Analysis VerifiedIssho-Otsusen, one of Noboribetsu's most iconic sources, naturally gushes approximately 1,900 liters per minute from the legendary Jigokudani (Hell Valley), the very heart of this storied onsen town. For generations, this potent source has soothed countless bath pilgrims, and its waters remain central to major facilities today, including the day-use bath Yumemoto Sagiri Yu. Characterized by its sulfurous aroma and strikingly strong acidic minerality, a soak in its milky-white waters offers an immersive taste of authentic onsen culture.
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 trace component with gentle antibacterial and anti-inflammatory action.
An iron-rich spring whose water turns yellow-brown to red-brown when exposed to air. Strong heat retention.
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.
At 72.5°C, Issho-Otsusen is exceptionally hot and highly acidic, making it a vigorous bathing experience. Rinse gently with fresh water after bathing to clear mineral residue from your skin. Avoid prolonged soaks and drink water frequently to stay hydrated throughout your visit.
Rich with pH 2.3 acidic strength and abundant sulfur compounds, this source is renowned for its powerful antimicrobial action on atopic dermatitis and chronic eczema. Its iron content delivers a deep, lingering warmth that radiates through the body long after bathing. Ideal for weekend wellness retreats seeking to revitalize fatigued muscles and spirits.
The strong acidity demands caution for sensitive-skinned individuals and elderly guests with dry skin—risk of thermal shock and irritation exists. Bathing is contraindicated during fever or for those with severe cardiac conditions.
※ See the analysis data below for detailed contraindications
ANALYSIS DATAView all analysis fields ▼
Source Info
- Source name
- 1号乙泉
- Spring type
- 酸性・含硫黄・鉄（Ⅱ, Ⅲ）－単純温泉（硫化水素型）
- Old spring type name
- 含硫化水素－酸性緑ばん泉
- Source temperature
- 72.5℃
- pH
- 2.3
- Flow rate
- 1,901 L/min
- Flow type
- 自然湧出
- Osmotic pressure
- 低張性
Analysis Document
- Analysis date
- 2019-07-02
- Analyst organization
- 北海道立衛生研究所
- Registration No.
- 北海道第1号
Cations
- Hydrogen ion H⁺
- 5.0 mg/kg
- Sodium ion Na⁺
- 36.0 mg/kg
- Potassium ion K⁺
- 5.6 mg/kg
- Ammonium ion NH₄⁺
- 1.3 mg/kg
- Magnesium ion Mg²⁺
- 5.7 mg/kg
- Calcium ion Ca²⁺
- 20.1 mg/kg
- Aluminum ion Al³⁺
- 29.1 mg/kg
- Iron(II) ion Fe²⁺
- 22.0 mg/kg
- Iron(III) ion Fe³⁺
- 4.6 mg/kg
- Total cations
- 0.13 mg/kg
Anions
- Fluoride ion F⁻
- 0.10 mg/kg
- Chloride ion Cl⁻
- 7.9 mg/kg
- Hydrogen sulfide ion HS⁻
- 0.00 mg/kg
- Thiosulfate ion S₂O₃²⁻
- 3.3 mg/kg
- Sulfate ion SO₄²⁻
- 543 mg/kg
- Bicarbonate ion HCO₃⁻
- 0.00 mg/kg
- Carbonate ion CO₃²⁻
- 0.00 mg/kg
- Bromide ion Br⁻
- 0.00 mg/kg
- Iodide ion I⁻
- 0.00 mg/kg
- Hydrogen sulfate HSO₄⁻
- 91.7 mg/kg
- Dihydrogen phosphate H₂PO₄⁻
- 0.40 mg/kg
- Total anions
- 0.65 mg/kg
Undissociated Components
- Sulfuric acid H₂SO₄
- 1.2 mg/kg
- Arsenious acid HAsO₂
- 0.20 mg/kg
- Metasilicic acid H₂SiO₃
- 76.6 mg/kg
- Metaboric acid HBO₂
- 21.3 mg/kg
- Total undissociated
- 0.10 mg/kg
Dissolved Gas
- Free carbon dioxide CO₂
- 44.0 mg/kg
- Free hydrogen sulfide H₂S
- 9.1 mg/kg
- Total dissolved gas
- 0.05 mg/kg
Trace Components
- Radon Rn
- 0.72 Bq/kg
Totals
- Total dissolved substances
- 0.88 mg/kg
- Component total
- 0.93 mg/kg
- Evaporation residue
- 0.95 mg/kg
Usage
- Heating
- No
- Dilution
- Yes
- 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, bruises, sprains in chronic stage), muscle stiffness due to motor paralysis, gastrointestinal dysfunction (indigestion, excessive intestinal gas), high blood pressure (mild), impaired glucose tolerance (diabetes), mild dyslipidemia, mild asthma or emphysema, hemorrhoid pain, autonomic instability, stress-induced symptoms (sleep disorders, depression), convalescence, fatigue recovery, health promotion, atopic dermatitis, psoriasis vulgaris, epidermal purulent disease, chronic eczema, peripheral circulatory failure
- General indications
- Chronic pain or stiffness in muscles and joints (rheumatoid arthritis, osteoarthritis, low back pain, neuralgia, frozen shoulder, bruises, sprains in chronic stage), muscle stiffness due to motor paralysis, gastrointestinal dysfunction (indigestion, excessive intestinal gas), high blood pressure (mild), impaired glucose tolerance (diabetes), mild dyslipidemia, mild asthma or emphysema, hemorrhoid pain, autonomic instability, stress-induced symptoms (sleep disorders, depression), convalescence, fatigue recovery, health promotion
- Contraindications
- Active stages of diseases (especially with fever), active tuberculosis, advanced malignant tumors or severe physical weakness such as severe anemia, severe heart or lung diseases that cause shortness of breath with slight movement, severe kidney diseases with edema, gastrointestinal bleeding, visible bleeding, acute exacerbation of chronic diseases, people with sensitive skin or mucous membranes, elderly people with dry skin.
Drinking
- Drinkability
- Not drinkable
