Yamaai-no-Yado KIYASUYA

Yamaai-no-Yado KIYASUYA uses two types of spring sources. The main source is a “Sodium - Chloride springs” (temperature 80.3°C) drawn from Sujiyu Onsen Supply Corporation.
The hydrogen ion concentration is pH 7.9 (Weakly alkaline).
Weakly alkaline hot springs help remove dead skin cells while bathing, leaving the skin smooth and silky after bathing, which is why they are often known as “Hot springs for beautiful skin”.
Among the cations, Sodium ions are the primary component, accounting for 87.72 mval% (milliequivalent percent). They help improve dry skin through their moisturizing effect, relax muscle tension and relieve pain, promote blood circulation to alleviate sensitivity to cold, stimulate metabolism, and contribute to a detoxifying effect.

On the other hand, Chloride ions account for 84.64 mval% of the anions.
Their effects include helping treat minor cuts through the bactericidal effects of salt, enhancing heat retention by allowing salt to seal the sweat glands, helping regulate the balance of the autonomic nervous system by raising body temperature, and promoting moisture retention through a protective salt coating on the skin.

The characteristics of chloride springs, together with explanations based on the Indications by spring quality, can be summarized as follows.
Because chloride springs have bactericidal effects, bathing in them may help suppress surface skin troubles such as Cuts. For this reason, they are often called “Hot springs for cuts”.
In addition, when bathing in a chloride spring, the salt content coats the body almost like a protective pack. This coating seals the sweat glands (the organs that secrete perspiration), slowing the loss of body heat after bathing and allowing the warming sensation to last longer.
For this reason, chloride springs are also known as “Hot springs for warmth”. They may help improve Peripheral circulatory disturbance and Sensitivity to cold.
Furthermore, the sustained warming effect is believed to help regulate the autonomic nervous system, suppress the secretion of stress hormones, enhance relaxation, and have positive effects on mental conditions such as Depression.
Chloride springs are also considered beneficial for Dry skin because, as mentioned above, the salt coating helps retain moisture in the skin.

Attention should also be paid to components that do not appear in the spring quality name itself.
Among the cations, Potassium ions (8.50 mval%) are the second most abundant component after the principal sodium ions.
Potassium ions are one of the minerals commonly found in Sodium – Chloride springs.
Within the human body, potassium functions mainly in intracellular fluid, while sodium functions mainly in extracellular fluid. Together, they help regulate nerve signal transmission, muscle contraction (including the relief of muscle cramps in the limbs), and fluid metabolism.
For this reason, potassium ions are considered an essential mineral involved in maintaining intracellular osmotic pressure and regulating electrolyte balance, and are thought to indirectly support the relaxing effects experienced during bathing.

Among the anions, Sulfate ions (13.77 mval%) are the second most abundant component after the principal chloride ions.
Sulfate ions help dilate blood vessels and promote blood circulation to the extremities, while the warming effect produced by the increased circulation is believed to contribute to regulation of the Autonomic nervous system.
They also help stimulate skin metabolism, giving the skin firmness and elasticity. In addition, they are thought to support recovery from skin troubles such as dry skin and minor cuts.

The spring contains 200 mg of Metasilicic acid per kilogram of spring water, more than 4 times the standard value (50 mg/kg).
It is a so-called Natural moisturizing component, and is sometimes used as some skin lotion products. After bathing in hot spring water, it helps to keep the skin moisturized. The presence of metasilicic acid is one of the conditions for being called “Hot springs for beautiful skin”.

Metaboric acid also contains 35.3 mg, which is more than 7 times the standard value (5 mg). Due to its Skin cleansing effects, it is thought to be effective in treating acne and other skin surface problems. This component is also used in some eye drops.

Among the cations, Lithium ions are present at 2.5 mg/kg, which is 2.5 times the hot spring standard value of 1 mg/kg. Lithium ions are said to have Calming effects that help suppress nervous excitement and promote relaxation.

In addition to the main Sodium – Chloride spring, another hot spring source is supplied by the Sujiyu Bunto Association and is primarily blended with the above source for use in the men’s and women’s large public baths.
Its spring quality is classified as a “Simple Hot Springs” with a pH of 7.0 (neutral) and a spring temperature of 91.5°C. Because it contains relatively mild mineral content and causes less stimulation, it is often described as a gentle type of hot spring water.
Due to its mild nature, which makes it suitable for everyone from children to the elderly, it is also known as “Hot springs for family”.
In the men’s and women’s large public baths, the Sodium – Chloride springs and the Simple Hot Springs are blended at an approximate ratio of 7:3.

Here, approximately 100 liters of hot spring water per minute are used in total from two separate sources, with the baths maintained in a free-flowing, continuously replenished style known as kakenagashi.
Kakenagashi is a luxurious style of hot spring bathing in which fresh hot spring water continuously flows into the bath, and the excess water is allowed to overflow and drain away without being reused.
As the maximum capacity of this inn is only 30 guests, the amount of hot spring water available per person works out to approximately 3.3 liters per minute.
As a general guideline, around 1 liter per minute per person is considered sufficient to maintain hygienic, non-recirculated hot spring baths. In other words, this inn possesses more than three times that amount of hot spring water.
The bath temperature is also adjusted naturally by changing the amount of hot spring water flowing into the tubs according to the outdoor temperature.
In midsummer, when the spring temperature becomes especially high, well water may occasionally be added to cool the baths, though the inn strives to keep the water as close to 100% pure hot spring water as possible.
It would not be an exaggeration to say that this inn teaches guests both the true appeal of hot springs and the importance of carefully considered hot spring management.

It should be noted that the hot spring water supplied by Sujiyu Onsen Supply Co., Ltd. (Sodium – Chloride springs) is a type of hot spring close to what is known as an “artificially enhanced spring”. In this system, high-temperature geothermal steam rising from underground is injected into existing hot spring water classified as a simple spring, allowing additional mineral components to dissolve into the water.
The source supplied by Sujiyu Onsen Supply Co., Ltd. is not created by directly piping used geothermal water discharged from the nearby Hatchobaru Geothermal Power Plant after power generation. Instead, geothermal steam from underground is injected into the Simple Hot Springs water supplied by the Sujiyu Bunto Association, enriching the water with additional mineral components before it is distributed to local facilities.
In other words, this system can be described as a “steam-injection artificially enhanced spring”, or a “hybrid enhanced spring in which geothermal steam-derived minerals are added to simple hot spring water”. It represents an advanced example of how geothermal power generation and hot spring tourism can coexist sustainably.

Although Japan is often described as a country poor in energy resources, it possesses the world’s third-largest geothermal resource potential, following the United States and Indonesia. This reflects the enormous geothermal potential of Japan, a country with significant volcanic and geothermal activity.
However, Japan’s actual geothermal power generation capacity cannot be considered among the world’s highest. Behind this are a variety of challenges, including the need to coordinate with the hot spring industry, the fact that many promising geothermal areas lie within national parks, and the high cost of drilling and development.
In particular, coexistence with hot spring resorts has long been a major issue. For this reason, cooperative examples such as the relationship between Hatchobaru Geothermal Power Plant and Sujiyu Onsen have become important models for the future of geothermal utilization.
Geothermal power is a form of renewable energy, like solar and wind power, yet it also possesses the characteristics of a “baseload power source”, capable of providing stable electricity generation with little dependence on weather conditions.
In the future, the value of geothermal energy may be reassessed even more highly.

Sujiyu Onsen is located in Aso-Kujyu National Park, surrounded by Mount Waita-san to the northwest, Mount Hitome-yama to the southwest, and the Kuju Mountain Range to the southeast.
The altitude is 1,000 meters, making it very pleasant in summer.
Also, the fresh greenery in spring, the autumn leaves in fall, and of course, the snowy landscape in winter will allow you to experience nature in all four seasons.
There are about 20 inns in Sujiyu Onsen, but “Yamaai-no-Yado KIYASUYA” is located in a quiet area a little far from the center of the hot spring resort area.
The approximately 2,000 tsubo (1.6 acres) site is covered by a wooded area, and is lined with 10 detached guest rooms, all built on a single-story structure.
All guest rooms are equipped with an open-air bath, and there are also large public baths for men and women, an open-air bath, two private open-air baths, and two family baths, offering a luxurious lineup of baths. Moreover, all of them are 100% free-flowing hot spring water.
The cuisine is uniquely KIYASUYA's, surrounded by deep green mountains and clear rivers.
The cuisine is based on locally produced and consumed foods, such as Yamame (landlocked masu salmon) and wild vegetables, without using anything from the sea.
The menu is full of flavor, highlighting the natural ingredients of each season.
Travel Journal