Ikaho Onsen Sogo-yu (Kogane-no-yu)

Analysis Unverified
伊香保温泉 総合湯(黄金の湯)
Golden Waters of Ikaho

Ikaho is an ancient spa praised in the Man'yoshu poetry anthology. In the Warring States era its stone-step street was laid out as a healing retreat for soldiers wounded at Nagashino, and the koma-guchi system that divides the spring water among the inns survives today. Kogane-no-yu rises clear, but its iron oxidizes in the air and tints the water tea-brown, as its golden name suggests. This neutral water rich in sulfate and bicarbonate warms the body to the core and has long been called a spring for fertility. It is a bath that carries Ikaho's history itself.

AI Generated
This source matches 3 spring types· Tap to switch
硫塩
SPRING TYPE
Sulfate Spring

Moisturizes the skin and forms a protective barrier, producing a deeply moisturizing effect. Can also soothe inflammations and help the skin heal.

See features & indications▾
Bathing indications
Cuts and grazesPeripheral circulatory failurePoor circulationDepressionXeroderma
Drinking indications
Biliary tract diseaseDyslipidemia (high cholesterol)Constipation

※ Only at facilities permitted to serve drinking water. 200–500 mL/day recommended.

Definition :Primary anion: sulfate ion.
Source: 環境省「あんしん・あんぜんな温泉利用のいろは」(監修:日本温泉気候物理医学会) ↗Read full article
PH VALUE
6.4
Neutral
Acidic ← 07 Neutral14 → Alkaline
Neutral (pH 6-7.5) per Japan Ministry of Environment classification. The pH range gentlest on the skin, suitable for long bathing.
TEMPERATURE
41.2℃
Warm Spring
Standard comfortable bath temperature. Warms the body thoroughly.
KEY MINERALS

The bar length shows how abundant each component is compared to thresholds that make it "distinctive" (therapeutic spring standards, beauty spring criteria, etc.).

Metasilicic acidSee detail
181 mg/kg

A natural moisturizer also used in skincare lotions. Forms a thin veil on the skin to reduce moisture loss after bathing.

Metaboric acidSee detail
8.3 mg/kg

A trace component with gentle antibacterial and anti-inflammatory action.

Bicarbonate ionSee detail
275 mg/kg

Softens dead skin cells for a silky bathing feel.

Iron(II) ionSee detail
7.2 mg/kg

Iron content that boosts heat retention and may tint the water.

Free carbon dioxideSee detail
172 mg/kg

Absorbed through the skin to gently promote peripheral circulation.

CHARACTER · COMPOSITION PROFILE
1234StimulationBactericidalSkin BeautyHeat RetentionRelaxation

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.

USAGE
Usage status is unknown — Information from facility postings or official sites has not been confirmed. Please check with staff on site.
▸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.

SENSORY TEST
Color
無色透明、僅かに茶色の浮遊物あり
EFFECTS
Spring-specific indications (bathing)
Cuts and grazesPeripheral circulatory failurePoor circulationDepressionXeroderma
General indications (bathing)
High blood pressure (mild)Rheumatoid arthritisAutonomic instabilityInsomniaChronic pain or stiffness in muscles and jointsMuscle stiffness due to motor paralysisGastrointestinal dysfunction
Contraindications
Acute illness (especially with fever)Active tuberculosisMalignant tumorsSevere heart diseaseRespiratory failureRenal failureBleeding disordersSevere anemiaAny actively progressing illnessPregnancy (especially early and late stages)
BATHING TIPS
AI Generated

At 41.2°C the source is on the mild side, suited to a longer soak that warms you to the core. The neutral pH 6.4 water is gentle, but its iron can stain white towels brown, so a dark towel is a safe choice.

EFFECT STORY
AI Generated

With 284 mg/kg of sulfate and 275 mg/kg of bicarbonate, this water encourages circulation for restorative warmth that lingers after bathing, and a slow soak may ease stiff muscles and joints.

CAUTIONS
AI Generated

Avoid bathing with fever or active illness, serious heart disease, respiratory or kidney failure, bleeding disorders or severe anemia. Skip bathing after drinking or right around meals, and drink water to avoid dizziness or dehydration on long soaks.

※ See the analysis data below for detailed contraindications

ANALYSIS DATAView all analysis fields ▼

Source Info

Source name
Ikaho Onsen Sogo-yu (Kogane-no-yu)
Spring type
Calcium-Sodium Sulfate, Bicarbonate and Chloride Hot Spring
Source temperature
41.2℃
pH
6.4
Flow rate
4,627 L/min
Osmotic pressure
低張性

Analysis Document

Analysis date
2017-05-30
Analyst organization
群馬県薬剤師会環境衛生試験センター

Cations

Sodium ion Na⁺
101 mg/kg
Potassium ion K⁺
8.7 mg/kg
Magnesium ion Mg²⁺
32.2 mg/kg
Calcium ion Ca²⁺
139 mg/kg
Aluminum ion Al³⁺
< 0.05 mg/kg
Manganese ion Mn²⁺
1.4 mg/kg
Iron(II) ion Fe²⁺
7.2 mg/kg
Total cations
0.29 mg/kg

Anions

Fluoride ion F⁻
< 0.1 mg/kg
Chloride ion Cl⁻
146 mg/kg
Sulfate ion SO₄²⁻
284 mg/kg
Bicarbonate ion HCO₃⁻
275 mg/kg
Carbonate ion CO₃²⁻
< 0.1 mg/kg
Total anions
0.70 mg/kg

Undissociated Components

Metasilicic acid H₂SiO₃
181 mg/kg
Metaboric acid HBO₂
8.3 mg/kg
Total undissociated
0.19 mg/kg

Dissolved Gas

Free carbon dioxide CO₂
172 mg/kg
Free hydrogen sulfide H₂S
0.00 mg/kg
Total dissolved gas
0.17 mg/kg

Totals

Total dissolved substances
1.2 mg/kg
Component total
1.4 mg/kg

Usage

Usage status
Unknown

Indications & Contraindications

Bathing indications
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)

Drinking

Drinkability
Not drinkable
FACILITY INFO
AI draft (unverified)
Official site
Tattoo
No tattoosGuests with tattoos, who are heavily intoxicated, or have infectious diseases are strictly prohibited from using the baths and other facilities.
Private bath (Kashikiri)
Available
About tattoos and onsen
Travelers with tattoos can still bathe comfortably in a private bath (Kashikiri) or a room with a private open-air bath.
Transit
From JR Shibukawa Station (JR Shibukawa Eki) on the Joetsu Line, take a local bus for approx. 25-30 minutes (get off at Ikaho Bus Terminal), or a taxi for approx. 20 minutes. From Shinjuku, take an express bus (JR Bus Joshu Yumeguri-go) for approx. 2.5 hours (get off at Ikaho Onsen), then walk for approx. 3-5 minutes.
Parking
Available (free), 120-150 passenger cars, outdoor, no reservation required.
Facilities
Large Public BathOpen-Air BathPrivate Rental BathLoungeKaraoke RoomBanquet HallConference RoomTable Tennis
House rules
Guests with tattoos, who are heavily intoxicated, or have infectious diseases are strictly prohibited from using the baths and other facilities.
This information may change without notice. Please contact the facility directly for accurate details.
How Long to Stay (Toji)
Start with 2 nights / 3 days

Japan’s Ministry of the Environment notes that even a short stay refreshes you. For a full therapeutic cure, around 2–3 weeks is the guideline.

More on toji length
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✨ The descriptions, catch phrases, and translations on this page are generated by AI (Claude). pH, temperature, and component values are OCR-extracted from the official analysis report. Learn more