Yumoto No. 29 & 46 Goko-sen

Analysis Verified
湯本 第29・46号混合泉
Blend of the Old Tokaido

Hakone-Yumoto Onsen, said to have opened in the Nara period, boasts the oldest history in Hakone. This Yumoto No. 29 & 46 Goko-sen is a blend of multiple sources from this historic spa town. It is used in public bathhouses along the old Tokaido road, having soothed weary travelers for centuries.

AI Generated
SPRING TYPE
Simple Spring

Spring water that is gentle on the skin with a very low likelihood of irritation. Safe for bathing infants and those with sensitive skin.

See features & indications
Bathing indications
Autonomic instabilityInsomniaDepression
Definition :Total dissolved solids (excluding gases) below 1,000 mg/kg; water temperature 25°C or above.
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
8.7
Alkaline
Acidic ← 07 Neutral14 → Alkaline
Alkaline (pH > 8.5). Strong soap-like cleansing and keratin-softening effects. The characteristic slippery feel begins to appear.
TEMPERATURE
45.8
Hot Spring
Hot. Warms the whole body quickly. For experienced bathers.
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
52.7 mg/kg

A natural moisturizer that leaves a hydrated feel on the skin.

Metaboric acidSee detail
3.3 mg/kg

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

Bicarbonate ionSee detail
71.5 mg/kg

Softens dead skin cells for a silky bathing feel.

Metaborate ionSee detail
1.0 mg/kg

Gentle antibacterial action that conditions the skin.

Fluoride ionSee detail
0.2 mg/kg

A trace antibacterial component that keeps skin clean.

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 unknownInformation 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
Smell
無臭
Taste
無味
EFFECTS
Spring-specific indications (bathing)
NeuralgiaMuscle painJoint painStiff shouldersMotor paralysisJoint stiffnessBruisesSprainsChronic digestive diseasesHemorrhoidsPoor circulationConvalescenceFatigue recoveryHealth promotion
Contraindications
Acute illness (especially with fever)Active tuberculosisMalignant tumorsSevere heart diseaseRespiratory failureKidney failureHemorrhagic diseasesSevere anemiaOther diseases in a progressive stagePregnancy (especially in early and late stages)
BATHING TIPS
AI Generated

The pH 8.7 alkaline water can soften skin, but long soaks may cause dryness; moisturize after bathing. The spring is warm at 45.8°C, so acclimate your body with "kake-yu" (scooping and pouring water on yourself) and start with shorter dips.

EFFECT STORY
AI Generated

With a high alkalinity of pH 8.7, this spring is ideal for achieving silky skin, often called "bihada-no-yu" (beautiful skin water) for its ability to gently exfoliate. Containing 52.7 mg/kg of metasilicic acid, it supports skin moisture, making it perfect for deep relaxation and rejuvenation.

CAUTIONS
AI Generated

Avoid bathing if you have general contraindications like acute illness, active tuberculosis, or severe heart disease. Pregnant individuals, especially in early and late stages, should be cautious. Sudden entry into hot water may cause dizziness.

※ See the analysis data below for detailed contraindications

ANALYSIS DATAView all analysis fields ▼

Source Info

Source name
Yumoto No. 29 & 46 Goko-sen
Spring type
Alkaline Simple Hot Spring
Old spring type name
単純温泉
Source temperature
45.8℃
pH
8.7
Osmotic pressure
低張性

Analysis Document

Analysis date
2012-11-01
Analyst organization
神奈川県温泉地学研究所
Registration No.
神奈川県知事登録第1号

Cations

Lithium ion Li⁺
0.01 mg/kg
Sodium ion Na⁺
95.5 mg/kg
Potassium ion K⁺
0.87 mg/kg
Ammonium ion NH₄⁺
0.00 mg/kg
Magnesium ion Mg²⁺
0.03 mg/kg
Calcium ion Ca²⁺
6.0 mg/kg
Aluminum ion Al³⁺
0.03 mg/kg
Manganese ion Mn²⁺
0.01 mg/kg
Iron(II) ion Fe²⁺
0.00 mg/kg
Zinc ion Zn²⁺
0.00 mg/kg
Lead ion Pb²⁺
0.00 mg/kg
Strontium ion Sr²⁺
0.00 mg/kg
Copper ion Cu²⁺
0.00 mg/kg
Cadmium ion Cd²⁺
0.00 mg/kg
Total cations
0.10 mg/kg

Anions

Fluoride ion F⁻
0.22 mg/kg
Chloride ion Cl⁻
80.3 mg/kg
Sulfate ion SO₄²⁻
45.2 mg/kg
Bicarbonate ion HCO₃⁻
71.5 mg/kg
Carbonate ion CO₃²⁻
2.8 mg/kg
Bromide ion Br⁻
0.16 mg/kg
Nitrate ion NO₃⁻
1.7 mg/kg
Hydrogen metasilicate HSiO₃⁻
5.2 mg/kg
Metaborate ion BO₂⁻
1.0 mg/kg
Total anions
0.21 mg/kg

Undissociated Components

Metasilicic acid H₂SiO₃
52.7 mg/kg
Metaboric acid HBO₂
3.3 mg/kg
Total undissociated
0.06 mg/kg

Dissolved Gas

Free carbon dioxide CO₂
0.22 mg/kg
Total dissolved gas
0.00 mg/kg

Totals

Total dissolved substances
0.37 mg/kg
Component total
0.37 mg/kg
Evaporation residue
0.31 mg/kg

Usage

Usage status
Unknown

Indications & Contraindications

Bathing indications
Neuralgia, Muscle pain, Joint pain, Stiff shoulders, Motor paralysis, Joint stiffness, Bruises, Sprains, Chronic digestive diseases, Hemorrhoids, Poor circulation, Convalescence, Fatigue recovery, Health promotion
Contraindications
Acute illness (especially with fever), Active tuberculosis, Malignant tumors, Severe heart disease, Respiratory failure, Kidney failure, Hemorrhagic diseases, Severe anemia, Other diseases in a progressive stage, Pregnancy (especially in early and late stages)

Drinking

Drinkability
Not drinkable
FACILITY INFO
Official site
Tattoo
Confirming
Room with private open-air bath
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.
Hours
Weekdays: 00:0023:59
Weekends & holidays: 00:0023:59
The locations of the men's and women's communal baths switch at midnight.
Transit
From Hakone-Yumoto Station (箱根湯本駅): Take the Ryokan Association shuttle bus (Course B, 200 yen one-way, departs approx. at :15 and :45 every hour) or walk uphill for approx. 20 minutes. Alternatively, from Hakone Tozan Bus Platform 4, take the bus bound for Hatajuku (Yama no Hotel / 畑宿), get off at Dai no Chaya (台の茶屋) bus stop, then walk for approx. 1 minute. By car: Approx. 15 minutes from Odawara-Nishi IC (小田原西IC).
Parking
10 free parking spaces available (no reservation required).
Facilities
Large Public BathOpen-air Bath (for guest rooms only)Foot BathWi-FiRefrigeratorElectric KettleTea SetHair Dryer
House rules
Please note that our facility does not have an elevator; guests will need to use the stairs. To minimize contact between guests, the number of yukata baskets in the communal indoor bath has been reduced. We kindly ask for your cooperation in staggering your bathing times if others are present (until the infectious disease situation stabilizes, please primarily enjoy the private open-air baths in your guest room). The BAR will remain closed for the time being (until the infectious disease situation stabilizes). Use by non-guests is also suspended. Check-in is at 15:00 (last check-in at 18:00), and check-out is at 11:00. Consecutive stays are limited to a maximum of 2 nights. Accommodation for children varies depending on the plan and room type (only Ruri rooms are available). Free accommodation is not available, and additional charges may apply.
This information may change without notice. Please contact the facility directly for accurate details.
Last updated: 6/1/2026
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