Naka no Yu
Analysis UnverifiedNaka no Yu is one of four springs of differing character that rise within about 50 meters of one another at Yunotai, said to be the oldest bathing ground of Nyuto Onsen. Locals have long called it the "eye spring," handed down as good for tired eyes. At around 45°C it is the gentlest of the four in temperature, and with the most bicarbonate it feels slightly silky. Surrounded by beech forest and a faint scent of sulfur, it invites a longer, unhurried soak.
The bar length shows how abundant each component is compared to thresholds that make it "distinctive" (therapeutic spring standards, beauty spring criteria, etc.).
A trace component with gentle antibacterial and anti-inflammatory action.
The source of the distinctive sulfur smell. Dilates blood vessels via skin and inhalation to strongly boost circulation.
A "beauty spring" that gently emulsifies dead skin cells, leaving skin smooth 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.
▸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 a neutral pH 6.7 the water is gentle, so settle in for a relaxed soak. Remove silver jewelry because of the sulfur, and avoid rinsing too thoroughly afterward.
With 1,075 mg/kg of bicarbonate softening the skin's surface, the water may support silky skin, while 7.6 mg/kg of free hydrogen sulfide links it to immune system stimulation, and chloride keeps the comfort going after the bath.
Because the water contains hydrogen sulfide, avoid long soaks in poorly ventilated spaces; those with sensitive skin should rinse lightly with fresh water afterward.
※ See the analysis data below for detailed contraindications
ANALYSIS DATAView all analysis fields ▼
Source Info
- Source name
- Naka no Yu
- Spring type
- Sulfur-containing Sodium-Calcium Chloride and Bicarbonate Hot Spring (hydrogen sulfide type)
- Source temperature
- 45.1℃
- pH
- 6.7
Analysis Document
- Analysis date
- 2014-08-25
- Analyst organization
- 株式会社 秋田県分析化学センター
- Registration No.
- 秋田第2号
Cations
- Lithium ion Li⁺
- 0.20 mg/kg
- Sodium ion Na⁺
- 727 mg/kg
- Potassium ion K⁺
- 25.0 mg/kg
- Ammonium ion NH₄⁺
- 5.4 mg/kg
- Magnesium ion Mg²⁺
- 57.0 mg/kg
- Calcium ion Ca²⁺
- 137 mg/kg
- Manganese ion Mn²⁺
- 1.1 mg/kg
- Lead ion Pb²⁺
- < 0.05 mg/kg
- Strontium ion Sr²⁺
- 0.90 mg/kg
- Barium ion Ba²⁺
- 0.20 mg/kg
- Cadmium ion Cd²⁺
- < 0.005 mg/kg
- Total cations
- 0.95 mg/kg
Anions
- Fluoride ion F⁻
- 1.0 mg/kg
- Chloride ion Cl⁻
- 823 mg/kg
- Hydrogen sulfide ion HS⁻
- 3.3 mg/kg
- Thiosulfate ion S₂O₃²⁻
- 3.6 mg/kg
- Sulfate ion SO₄²⁻
- 167 mg/kg
- Bicarbonate ion HCO₃⁻
- 1075 mg/kg
- Bromide ion Br⁻
- 1.5 mg/kg
- Iodide ion I⁻
- 0.70 mg/kg
- Nitrate ion NO₃⁻
- 4.8 mg/kg
- Hydrogen phosphate HPO₄²⁻
- 0.20 mg/kg
- Total anions
- 2.1 mg/kg
Undissociated Components
- Metasilicic acid H₂SiO₃
- 53.3 mg/kg
- Metaboric acid HBO₂
- 45.0 mg/kg
- Total undissociated
- 0.10 mg/kg
Dissolved Gas
- Free carbon dioxide CO₂
- 148 mg/kg
- Free hydrogen sulfide H₂S
- 7.6 mg/kg
- Total dissolved gas
- 0.16 mg/kg
Totals
- Total dissolved substances
- 3.1 mg/kg
- Component total
- 3.3 mg/kg
Usage
- Heating
- No
- Dilution
- Yes（白湯の掲示『浴槽温度が高い期間（5〜11月）のみ加水しています』。秘湯の会『加水あり』。黒湯は通年加水、中の湯・滝の湯は7〜9月のみ加水（各掲示）。）
- Recycle / Filter
- No
- Additives
- No
- Disinfection
- No
Indications & Contraindications
- Bathing indications
- Atopic dermatitis, Plaque psoriasis, Chronic eczema, Epidermal suppuration, 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), Severe chronic dermatitis (sulphur springs)
Drinking
- Drinkability
- Not drinkable
