Sakura no Yu

Analysis Unverified
桜の湯
Silken Spring of Nasu

The Sakura no Yu source rises unaided in the Nasu range, high in the Okunasu district of Omaru Onsen, delivering 189 litres a minute without a pump. The waters of this pocket of the mountains have been tended for more than two centuries, and in the Meiji era General Nogi Maresuke is said to have come each year to take the cure. Emerging at 77.9°C, the water is all but colourless and clear, neither scented nor tasting of much. Rich in metasilicic acid, it feels rounded on the skin and leaves a soft, unhurried lightness once the bathing is done. It suits anyone who wants to steep quietly, without sting or drama, in the hush of the mountains.

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
7.3
Neutral
Acidic ← 07 Neutral14 → Alkaline
Upper bound of neutral (pH 7.5). Approaching mildly alkaline, the boundary where skin starts to feel smooth.
TEMPERATURE
77.9
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.).

Metasilicic acidSee detail
319 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
17.3 mg/kg

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

Sulfate ionSee detail
380 mg/kg

Soothes the skin and gently improves circulation.

Magnesium ionSee detail
23.5 mg/kg

Transdermal absorption gently supports skin hydration and muscle relaxation.

Calcium ionSee detail
69.3 mg/kg

Gentle astringent action that conditions the skin.

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
Free-Flowing Onsen
Pure spring water — no dilution, no recirculation
HeatedNo
DilutedNo
RecycledNo
FilteredNo
DisinfectedNo
AdditivesNo
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
ほとんど無色澄明
Smell
無臭
Taste
無味
EFFECTS
Spring-specific indications (bathing)
Autonomic 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)
BATHING TIPS
AI Generated

The source emerges at 77.9°C, so test the water at the rim before sinking in to the shoulders. This near-neutral simple spring is gentle, but three short soaks of five to ten minutes ask less of the body than one long one. Drink water afterwards.

EFFECT STORY
AI Generated

Neutral at pH 7.35 and carrying 319 mg/kg of metasilicic acid, this water seems to hold moisture against the skin — a good choice on a day you are after silky skin. Being a mild simple spring, it also lends itself to the deep relaxation sought after a long walk in the hills.

CAUTIONS
AI Generated

Avoid bathing with acute illness or fever, active tuberculosis, malignant tumours or serious heart disease. The source is hot, so anyone prone to light-headedness should keep soaks short.

※ See the analysis data below for detailed contraindications

ANALYSIS DATAView all analysis fields ▼

Source Info

Source name
Sakura no Yu
Spring type
Simple Hot Spring
Source temperature
77.9℃
pH
7.35
Flow rate
189 L/min
Flow type
自然湧出
Osmotic pressure
低張性

Analysis Document

Analysis date
2015-11-09
Analyst organization
一般社団法人 栃木県薬剤師会 検査センター
Registration No.
14栃薬第1号

Cations

Hydrogen ion H⁺
0.00 mg/kg
Lithium ion Li⁺
0.00 mg/kg
Sodium ion Na⁺
50.7 mg/kg
Potassium ion K⁺
24.0 mg/kg
Ammonium ion NH₄⁺
0.00 mg/kg
Magnesium ion Mg²⁺
23.5 mg/kg
Calcium ion Ca²⁺
69.3 mg/kg
Aluminum ion Al³⁺
0.00 mg/kg
Manganese ion Mn²⁺
0.30 mg/kg
Iron(II) ion Fe²⁺
0.00 mg/kg
Iron(III) ion Fe³⁺
0.00 mg/kg
Zinc ion Zn²⁺
0.00 mg/kg
Lead ion Pb²⁺
< 0.01 mg/kg
Strontium ion Sr²⁺
0.00 mg/kg
Barium ion Ba²⁺
0.00 mg/kg
Copper ion Cu²⁺
< 0.01 mg/kg
Cadmium ion Cd²⁺
< 0.01 mg/kg
Total cations
0.17 mg/kg

Anions

Fluoride ion F⁻
0.00 mg/kg
Chloride ion Cl⁻
1.4 mg/kg
Hydroxide ion OH⁻
0.00 mg/kg
Hydrogen sulfide ion HS⁻
0.00 mg/kg
Thiosulfate ion S₂O₃²⁻
0.00 mg/kg
Sulfate ion SO₄²⁻
380 mg/kg
Bicarbonate ion HCO₃⁻
13.1 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⁻
0.00 mg/kg
Hydrogen thiosulfate HS₂O₃⁻
0.00 mg/kg
Nitrite ion NO₂⁻
0.00 mg/kg
Nitrate ion NO₃⁻
0.20 mg/kg
Dihydrogen phosphate H₂PO₄⁻
0.00 mg/kg
Hydrogen phosphate HPO₄²⁻
0.00 mg/kg
Phosphate ion PO₄³⁻
0.00 mg/kg
Arsenite ion AsO₂⁻
0.00 mg/kg
Sulfide ion S²⁻
0.00 mg/kg
Hydrogen metasilicate HSiO₃⁻
0.00 mg/kg
Metasilicate ion SiO₃²⁻
0.00 mg/kg
Metaborate ion BO₂⁻
0.00 mg/kg
Total anions
0.40 mg/kg

Undissociated Components

Sulfuric acid H₂SO₄
0.00 mg/kg
Phosphoric acid H₃PO₄
0.00 mg/kg
Arsenious acid HAsO₂
0.00 mg/kg
Metasilicic acid H₂SiO₃
319 mg/kg
Metaboric acid HBO₂
17.3 mg/kg
Total undissociated
0.34 mg/kg

Dissolved Gas

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

Totals

Total dissolved substances
0.90 mg/kg
Component total
0.90 mg/kg
Evaporation residue
0.89 mg/kg

Usage

Heating
No
Dilution
No
Recycle / Filter
No
Additives
No
Disinfection
No

Indications & Contraindications

Bathing indications
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)

Drinking

Drinkability
Not drinkable
FACILITY INFO
AI draft (unverified)
Official site
Tattoo
No tattoosGuests with tattoos are strictly prohibited from using the facilities, in accordance with police guidance.
Private bath (Kashikiri)
Available
Bathing wear (Yuami-gi)
Free rental
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: 11:3015:00
Weekends & holidays: 11:3015:00
Last admission for day-use bathing is 14:30. Overnight guests can use the baths 24 hours, except during cleaning (10:00-11:30).
Closed days: Irregular holidays
Transit
Approx. 70 min by local bus (Kanto Bus) from JR Tohoku Shinkansen Nasushiobara Station (JR Tōhoku Shinkansen Nasushiobara Eki) (reservation required 2 days in advance, round trip 500 yen). Approx. 30 min by car from Tohoku Expressway Nasu IC (Tōhoku Jidōshadō Nasu IC).
Parking
Available, 30 spaces, free. *This is the Prefectural Oomaru Parking Lot (Ken'ei Oomaru Chūshajō) located just before the ryokan.
Day use fee
¥1,300Adult price. Children (3 years old to elementary school age) 1,000 yen. Includes face towel and bathing wear.
Facilities
Public BathOpen-air BathPrivate BathDrinking SpringGift ShopTea LoungeRest Area
House rules
No photography in the bath area
The facility is built on a slope, so there are many stairs. Please contact us in advance if you have difficulty walking.
Sources
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