Open-air Bath in the Guestroom, Overlooking the Hakone Mountain Range


箱根吟遊 日本語サイト 

  Sodium-Chloride Springs


ナトリウム-塩化物泉(低張性 弱アルカリ性 高温泉)
(Hypotonic, Weak alkaline, Hyperthermal Springs)

Ideal for people like this

Those with cold sensitivity or dry skin, or those who want to heal wounds quickly
100-1, Miyanoshita, Hakone-machi, Ashigarashimo-gun, Kanagawa-ken, 250-0404, JAPAN
〒250-0404 神奈川県足柄下郡箱根町宮ノ下100-1

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official website

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Hotel report

Hot Spring Power Chart (6-point scale)

※For Ginyu Spa’s private open-air bath

Passed Items of the Onsen Qualifications


Temperature above 25℃ 52.6℃ Passed
Dissolved substances (excluding gaseous substances) over 1,000 mg/kg in total 1,142mg/kg Passed
Metasilicic acid over 50 mg/kg 103mg/kg Passed
Metaboric acid over 5 mg/kg 14.8mg/kg Passed

Hydrogen Ion Concentration (pH)

Hydrogen ion concentration (pH)
Gentle on skin with little irritations

5 Elements of Hot Springs for Beautiful Skin

Number of applicable elements : 2

Skin whitening effect Skin cleansing effect Skin reviving effect Skin smoothing effect Skin moisturizing effect
Sulfur Springs Hydrogen Carbonate Springs Sulfate Springs Alkaline Metasilicic acid

Hot Spring Source Usage

Water added Heated Disin fected Circulated Bath additive
No Yes/No Yes Yes/No No
※Large Public Bath・・・Circulated and disinfected while using water directly from the spring source.
※Open-air Bath in the Guest Room・・・Circulated and disinfected (when the amount of hot water in the bathtub decreases, new water from the source is added)
※Ginyu Spa private open-air bath・・・100% flowing directly from the source
Percentage of hot spring source 100%
Replacement frequency of hot spring water
Large Public Bath : Once every 2 days
Open-air Bath in the Guest Room : Every day
Ginyu Spa private open-air bath : Every day
Yield of hot spring water Hot spring water is drawn from the in-house source (Miyanoshita Onsen) of the pumping system located on the grounds of the sister inn "Musashino Bekkan".
How hot spring water is drawn Drawn by a pipe
Distance from the source to the bathtub About 1 km (3,280 ft)
How water temperature is adjusted Large Public Bath, Open-air Bath in the Guest Room:Heating and adjusting as needed
Ginyu Spa private open-air bath:Adjusting the hot water amount
Drinking Spring None
“Gensen-Kakenagashi” Bath
A hot spring bath supplied with water directly from the source without any alterations.
Private open-air bath × 1 bath

Hot Spring Composition Table

Hot Spring Analysis Report

Spring Quality Sodium - Chloride Springs (Hypotonic, weak alkaline, and hyperthermal springs)
Color of hot spring Colorless and transparent無色透明
Scent of hot spring Odorless
Dissolved substances 1,142mg/kg(Sum of components (1) + (2) + (3), excluding gaseous substances)
Temperature of spring 52.6℃
pH 8.4(weak alkaline)
Yield About 90 liters per minute

Amount of hot spring use per person (yield / bath capacity):About 1.2 liters/person (maximum capacity of 75 people)
The requirements to satisfy kakenagashi (flowing directly from the source) and amount of hot spring required for bathtub management are more than 1 liter/minute per person who enters the bathhouse (cited from "Gensen-Yuyado").

Hot Spring Composition (Amount contained in 1 kg of spring)

Cation mg mval mval%
Lithium Ion(Li+ 0.45 0.09 0.54
Sodium Ion(Na+ 321 13.94 84.16
Potassium Ion(K+ 25.0 0.65 3.92
Magnesium Ion(Mg2+ 2.98 0.30 1.80
Calcium Ion(Ca2+ 31.8 1.58 9.56
Strontium Ion(Sr2+ 0.05 0.00 0.01
Ferrous Ion(Fe2+ 0.17 0.00 0.00
Aluminum Ion(Al3+ 0.02 0.00 0.00
Manganese Ion(Mh2+ 0.06 0.00 0.00
Zinc Ion(Zn2+ 0.12 0.00 0.00
Cations Total(1) 381.65 16.56 100.00
Anion mg mval mval%
Fluoride Ion(F- 0.14 0.01 0.05
Chloride Ion(Cl- 472 13.31 81.16
Bromide Ion(Br- 0.95 0.01 0.06
Sulfate Ion(SO42- 55.7 1.16 7.07
Bicarbonate Ion(HCO3-) 76.1 1.25 7.64
Carbonate Ion(CO32- 5.83 0.15 0.89
Nitrate Ions(NO3- 1.58 0.02 0.15
Metasilicate Ion(HSiO3- 20.4 0.28 1.70
Metaborate Ion(NO3- 9.11 0.21 1.27
Anion Total(2) 641.81 16.39 100.00
Undissociated Components mg mmol
Metasilicic Acid(H2SiO3 103 13.28
Metaboric Acid(HBO2 14.8 0.34
Undissociated Components Total(3) 117.80 13.62
Dissolved Gas Components mg mmol
Free Carbon Dioxide(CO2 0.08 0.00
Dissolved Gas Components Total(4) 0.08 0.00
Other Trace Components
Copper Ion: 0.00 mg(Cu2+)/ kg, Lead Ion (Pb2+): 0.01 mg / kg, Cadmium Ion(Cd2+): 0.00 mg / kg, Total Arsenic(As): 0.568 mg / kg, Total Mercury(Hg): 0.000 mg / kg

※The components in the yellow box are required to determine spring quality or to qualify as a hot spring (as defined in Japan).

Indications for Bathing (Revised on July 1, 2014)

Indications by Spring Quality for Bathing

Cuts, Peripheral circulatory disturbance, Cold sensitivity, State of depression, Dry skin

General Indications for Bathing

Chronic pain or stiffness of muscles or joints (chronic stages of rheumatoid arthritis, osteoarthritis, lower back pain, neuralgia, frozen shoulder, bruises, sprains, etc.),
muscle stiffness by motor paralysis, sensitivity to the cold, peripheral circulatory disturbance,
decline of gastrointestinal function (slow digestion, intestinal gas formation, etc.),
mild hypertension, impaired glucose tolerance (diabetes), mild hypercholesterolemia,
mild asthma or emphysema, hemorrhoidal pain, autonomic instability,
various symptoms from stress (sleep disorders, depression, etc.),
recovering from illness, recovery from fatigue, and promotion of health

Contraindications by Spring Quality for Bathing


General Contraindications for Bathing

Period of illness (especially when accompanied by fever), active tuberculosis,
advanced malignant tumor, or in cases of severe physical weakness, such as severe anemia,
severe cardiac or lung disease involving feelings of suffocation with little body movement,
severe kidney disease involving edema, gastrointestinal bleeding,
visible bleeding, and acute advanced stage of chronic disease

Indications by Spring Quality for Drinking

Atrophic gastritis, constipation *Not to be consumed because permission not obtained

The above indications and contraindications for hot springs were revised on July 1, 2014.

Date of Analysis (The above hot spring composition table is cited from the survey data of the following institution)

December 20, 2007 (Hot Springs Research Institute of Kanagawa)

  • ※Indications and contraindications for hot springs are in accordance with "The Standard Methods of Analysis for Mineral Springs" revised on July 1, 2014.
  • ※宿よりデータを提供して頂きました。

Hot Spring Legends and More

Traditionally documented efficacies

"Nanayu no Shiori", an Edo period guidebook on Hakone's seven hot springs, lists the efficacies of Miyanoshita Onsen as follows: Headache, stiffness in the shoulders, lower back pain, beriberi (disease resulting in heart failure and peripheral neuropathy), pain occurring in the abdomen and chest, hemiplegia or paralysis in the hands and legs occurring from cerebral hemorrhage, colic, muscle and joint pain, leg cramps, asthma, dizziness, blood clots, bruises, hemorrhoids, sprains, and vaginal discharge.

Historical figures who bathed in this hot spring

U.S. Army General Douglas MacArthur (1880-1964), U.S. President Dwight D. Eisenhower (1890-1969), comedian Charles Chaplin (1889-1977), social activist Helen Keller (1880-1968), musician John Lennon (1940-1980), and many others.

Hot Spring (Onsen) Report

The spring quality of Hakone Ginyu is sodium-chloride springs with weak alkalinity (pH 8.4).
First of all, note that it is weak alkaline.
Because human skin is generally slightly acidic, soaking in alkaline hot springs dissolves old cuticles on the skin and makes it feel smooth.
Because of this property, hot springs that are (weak) alkaline are called “hot springs for beautiful skin (bihada-no-yu)”.
It should not be overlooked that it is a chloride spring, that is, a hot spring that contains salt.
Indications by spring quality of chloride springs include cuts, peripheral circulatory disturbance, cold sensitivity, state of depression, and dry skin.
The salt mask also reduces skin dryness after bathing.
In addition, as salt has antimicrobial properties, it is effective against cuts and bruises.
The salt mask also reduces skin dryness after bathing.
In addition, as salt has antimicrobial properties, it is effective against cuts and bruises.
Therefore, chloride springs are also called “hot springs for wounds (kizu-no-yu)”.
Also note the metasilicic acid. This is because it contains 103 mg of metasilicic acid per kilogram of spring water.
According to the Japanese hot spring standard, hot springs must contain 50 mg or more of metasilicic acid per 1 kg of spring water to be approved as a hot spring.
This means that this hot spring contains more than twice the standard value (50 mg) of metasilicic acid.
It is said to be a natural moisturizer and is sometimes used as an ingredient in lotion.
One of the conditions for being called “hot springs for beautiful skin (bihada-no-yu)” is that it contains an abundance of metasilicic acid.
This spring also contains 14.8 mg of metaboric acid, which is also nearly three times the Japanese hot spring standard value (5 mg).
Metaboric acid has a cleansing effect on the skin and is thought to be effective in treating skin problems such as acne.
It also has antibacterial properties and is used as an ingredient in eye drops.
At this inn, hot springs in the large public baths and open-air baths in the guest rooms are circulated and disinfected, while the open-air bath in the esthetic facility Ginyu Spa is 100% flowing directly from the source.
Ginyu Spa is basically limited to esthetic customers only, but in the evenings, the entire esthetic facility can be rented out to one group per day.
If you want to feel the power of hot springs to the fullest, this private open-air bath at Ginyu Spa is recommended.
Also, as mentioned earlier, it is perfect for finishing up after a spa treatment as it covers your body like a natural mask.
To be able to experience the hot springs at this inn in Hakone, being close to Mt. Fuji, is sure to be a trip to remember.

Ginyu Spa private open-air bath Open-air bath and inner bath in the guest room “Meigetsu”
“Ginyu Spa” private open-air bath Open-air bath and inner bath in the guest room “Meigetsu”
This is the only bathtub in the inn with 100% free-flowing hot spring from the source.
During the day, it is used by esthetic customers, but at night, the entire esthetic facility can be rented out to one group per day. Every place in the private open-air bath is lit up, including the trees, creating a fantastic atmosphere.
All of the 20 guest rooms are equipped with an open-air bath. Since the inn is built to cling onto a cliff, you can enjoy the view of the Hakone mountain range from the open-air bath in any room. In addition to the open-air bath, there is also an indoor bath booth surrounded by transparent acrylic panels.
Open-air bath in the guest room “seishuku” Large Public Open-air Bath and Inner Bath “Tsukishiro”
Open-air bath in the guest room “seishuku” Large Public Open-air Bath and Inner Bath “Tsukishiro”
The inn has one maisonette-type guest room available. The view from the rooms utilizes the advantages of corner rooms, and bathing in the hot water with a view of the Hakone mountain range offers an outstanding sense of freedom. The sofa on the terrace also adds to the resort atmosphere. There are two large baths for female and male guests that interchange depending on the time of day. Large public open-air bath "Tsukishiro" is also known as an "infinity open-air bath" because the edge of the bathtub and the handrails are all invisible from your sight when you soak in. You feel like floating on the air.

Facility Report

“Hakone Ginyu”, located in Hakone Miyanoshita Onsen, is a popular hot spring inn(Japanese onsen ryokan) that often described as “a Japanese inn that is difficult to book” by various media.
The exotic atmosphere of Miyanoshita onsen resort and the oriental style of Japanese onsen ryokan simply matched perfectly.
Looking out from the inn, the view of the Hakone mountain range is magnificent; gaze at and you will find it looks like a greenish mossy garden.
Or, like an island in a vast ocean.
Both dinner and breakfast are basically served in the guest rooms.
You can enjoy kaiseki ryori (one type of Japanese course meal), in which the ingredients are carefully selected to give a sense of the goodness of Japan.
For breakfast, you can choose between Japanese and Western food, which is a nice touch.
After this inn was born, people in the inn industry came to inspect it, learning about its great success, and similar inns were created all over Japan.
However, after all, they cannot surpass the original Hakone Ginyu.
This is because Hakone Ginyu is the pioneer who created the current trend of Japanese inns by adding a superb view and hospitality to all rooms having an open-air bath.

Rates Data

Room with two meals From 29,000 yen per night(without tax)
Room with breakfas Not available
Overnight stay without meals Not available
Rates for one person (room with two meals) From 43,500 yen per night
Private bath rates for hotel guests Included in the price of Ginyu Spa
Without stay rates Not available
Use of private bath without stay Not available

Facility Data

Founded in 1951
Check in 2:00 PM
Check out 11:00 AM
Location of the inn Environment of the inn Mountains, ravines, and gardens
Number of rooms 20 rooms total
17 Japanese-style rooms, 3 Japanese-Western style rooms - All 20 rooms have an open-air bath
Capacity 75 people
Parking 15 cars
Facilities Lounge, cafe, bar, spa, and store
Internet Wi-Fi available throughout the building
Handicapped-accessible rooms Partly Supported
Toilet with shower Equipped

Transportation Access

By train A 3-minute walk from Miyanoshita Station on the Hakone Tozan Railway
By bus A minute walk from the Miyanoshita bus stop on the Hakone Tozan Bus
Shuttle bus None
By car Odawara-Atsugi Road → National Route 1 → Miyanoshita → Hakone Ginyu (about 20 minutes from Odawara West IC)
Address Kanagawa Prefecture/Hakone, Miyanoshita Onsen/Hakone Ginyu
100-1, Miyanoshita, Hakone-machi, Ashigarashigashimo-gun, Kanagawa, 250-0404, Japan

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Mayu Araki

The facilities, the room, the bath... Everything was amazing and I felt like I was in a work of art. It was a waste to get out of the hot spring when the heat retention effect is enough to make you feel warm and fuzzy!

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