Okamotoya Ryokan Gensen

Analysis Unverified
岡本屋旅館
Milky Blue Waters of Myoban

Myoban Onsen prospered in the Edo period through alum production and still keeps rows of thatched huts where yunohana sulfur flowers are made. Here the Okamotoya Ryokan source gushes naturally at 74.4°C in Myoban 3-kumi; colorless as it emerges, it turns a milky, bluish white once it meets the air in the bath. Its acidity gently loosens old skin cells, leaving a soft, light feeling afterward, and it suits anyone who wishes to steep in dense sulfur water amid mountain steam.

AI Generated
This source matches 3 spring types· Tap to switch
酸
SPRING TYPE
Acidic Spring

These springs have a strong antibacterial effect which can result in a mild tingling sensation on contact. Effective for healing wounds and relieving inflammatory skin conditions. Those with sensitive skin should rinse with fresh water after bathing.

See features & indications▾
Bathing indications
Atopic dermatitisPlaque psoriasisEpidermal suppurationImpaired glucose tolerance (diabetes)
Cautions
  • ⚠ 皮膚または粘膜の敏感な方、高齢者の皮膚乾燥症の方は禁忌です。
  • ⚠ 肌が弱い方は入浴後に真湯で洗い流してください。
Definition :Contains 1 mg/kg or more of hydrogen ions.
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
2.6
Acidic
Acidic ← 07 Neutral14 → Alkaline
Acidic spring (pH < 3). Antibacterial and skin-softening effects. Known for a refreshing bathing experience.
Caution: Avoid prolonged bathing. Rinse with fresh water after bathing. Not recommended for those with open wounds.
TEMPERATURE
74.4℃
Very Hot Spring
Near boiling, extremely hot. Requires substantial cooling or dilution.
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.).

Free hydrogen sulfideSee detail
9.0 mg/kg

The source of the distinctive sulfur smell. Dilates blood vessels via skin and inhalation to strongly boost circulation.

Aluminum ionSee detail
4.3 mg/kg

Tightens the skin and balances sebum.

Metasilicic acidSee detail
153 mg/kg

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

Sulfate ionSee detail
254 mg/kg

Soothes the skin and gently improves circulation.

Iron(II) ionSee detail
2.4 mg/kg

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

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
無色澄明
Smell
弱硫化水素臭
Taste
中酸味
EFFECTS
Spring-specific indications (bathing)
Atopic dermatitisPlaque psoriasisEpidermal suppurationImpaired glucose tolerance (diabetes)Chronic eczemaAutonomic instabilityInsomniaDepression
General indications (bathing)
High blood pressure (mild)Rheumatoid arthritisChronic 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)Sensitive skin or mucous membranes, eye conditions (acidic springs)Severe chronic dermatitis (sulphur springs)
BATHING TIPS
AI Generated

As a pH 2.6 acidic spring containing hydrogen sulfide, it is best enjoyed in soaks of about five to ten minutes with rests in between. Those with sensitive skin should rinse with fresh water afterward, and silver jewelry should be removed to prevent tarnishing.

EFFECT STORY
AI Generated

With pH 2.6 acidity and 9.0 mg/kg of free hydrogen sulfide, this sulfur spring is traditionally associated with immune system stimulation. Its acidity and 153.0 mg/kg of metasilicic acid loosen old skin cells toward silky skin, suiting days when you wish to refresh your skin or care for your body.

CAUTIONS
AI Generated

Avoid long soaks in this acidic sulfur spring, take care if your skin or mucous membranes are sensitive, and mind hydrogen sulfide in poorly ventilated spaces.

※ See the analysis data below for detailed contraindications

ANALYSIS DATAView all analysis fields ▼

Source Info

Source name
Okamotoya Ryokan Gensen
Spring type
Acidic Sulfur-containing Simple Hot Spring (hydrogen sulfide type)
Old spring type name
酸性単純硫化水素泉
Source temperature
74.4℃
pH
2.6
Flow type
自然湧出
Osmotic pressure
低張性

Analysis Document

Analysis date
2015-06-22
Analyst organization
大分県薬剤師会検査センター
Registration No.
大分県第3号

Cations

Hydrogen ion H⁺
2.5 mg/kg
Sodium ion Na⁺
20.7 mg/kg
Potassium ion K⁺
5.1 mg/kg
Magnesium ion Mg²⁺
8.3 mg/kg
Calcium ion Ca²⁺
20.2 mg/kg
Aluminum ion Al³⁺
4.3 mg/kg
Manganese ion Mn²⁺
0.70 mg/kg
Iron(II) ion Fe²⁺
2.4 mg/kg
Lead ion Pb²⁺
< 0.01 mg/kg
Strontium ion Sr²⁺
0.20 mg/kg
Copper ion Cu²⁺
< 0.05 mg/kg
Cadmium ion Cd²⁺
< 0.001 mg/kg
Total cations
0.06 mg/kg

Anions

Fluoride ion F⁻
0.20 mg/kg
Chloride ion Cl⁻
3.3 mg/kg
Thiosulfate ion S₂O₃²⁻
0.40 mg/kg
Sulfate ion SO₄²⁻
254 mg/kg
Hydrogen sulfate HSO₄⁻
21.4 mg/kg
Dihydrogen phosphate H₂PO₄⁻
0.50 mg/kg
Total anions
0.28 mg/kg

Undissociated Components

Sulfuric acid H₂SO₄
0.10 mg/kg
Phosphoric acid H₃PO₄
0.00 mg/kg
Arsenious acid HAsO₂
0.00 mg/kg
Metasilicic acid H₂SiO₃
153 mg/kg
Metaboric acid HBO₂
0.00 mg/kg
Total undissociated
0.15 mg/kg

Dissolved Gas

Free carbon dioxide CO₂
9.7 mg/kg
Free hydrogen sulfide H₂S
9.0 mg/kg
Total dissolved gas
0.02 mg/kg

Trace Components

Radon Rn
< 7.4 Bq/kg

Totals

Total dissolved substances
0.50 mg/kg
Component total
0.52 mg/kg
Evaporation residue
0.49 mg/kg

Usage

Usage status
Unknown

Indications & Contraindications

Bathing indications
Atopic dermatitis, Plaque psoriasis, Epidermal suppuration, Impaired glucose tolerance (diabetes), Chronic eczema, Autonomic instability, Insomnia, Depression
General indications
High blood pressure (mild), Rheumatoid arthritis, 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), Sensitive skin or mucous membranes, eye conditions (acidic springs), Severe chronic dermatitis (sulphur springs)

Drinking

Drinkability
Not drinkable
FACILITY INFO
AI draft (unverified)
Official site
Tattoo
Cover allowedSmall tattoos are permitted if covered with a tattoo cover-up seal.
About tattoos and onsen
Transit
15 minutes by car from JR Beppu Station (JR Beppu Eki). Alternatively, take Kamenoi Bus (Kamenoi Bus) No. 5, 24 (for APU), or 41 (for Safari) for about 30 minutes, then 1 minute walk from Myoban (Myoban) bus stop. 5 minutes by car from Oita Expressway Beppu IC (Oita Jidoshado Beppu IC), or 5 minutes by car from Beppuwan SA Smart IC (Beppuwan SA Smart IC) (ETC only exit).
Parking
Available. 8 spaces. Free. Reservation required. Please inform us of your vehicle type in advance as parking is by reservation only. Microbuses and large buses cannot be parked.
Day use fee
¥800
Facilities
Public BathOpen-air BathVending MachinesSmoking AreaRestaurant / Dining AreaBook Corner
House rules
In Japanese onsen, bathing naked is standard; swimsuits or towels are not permitted. There is no elevator in the building, and there are stairs with high steps. Children under elementary school age are not permitted.
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
✨ 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