Natural Hot Spring Water and Traditional Benefits
The spring water at Hoshi Onsen is a calcium-sodium sulfate spring, also known as a gypsum spring. The water is clear, colorless, and pleasantly gentle on the skin. The source temperature is approximately 43°C.
Traditionally, the spring has been associated with benefits for conditions such as digestive disorders, burns, and arteriosclerosis, and it has been enjoyed for centuries as a destination for toji, the Japanese tradition of restorative hot spring bathing.
One of the greatest attractions of Hoshi Onsen is its natural spring water. The water rises directly from underground and flows into the baths without artificial pumping, allowing visitors to experience the spring in an exceptionally natural setting.
A 1,200-Year Legend and Long History
The exact date when Hoshi Onsen was first discovered is unknown, but its history is traditionally estimated to go back approximately 1,200 years. According to local legend, the famous Buddhist monk Kobo Daishi discovered the spring while traveling through the region.
The inn itself was established in 1875, during the Meiji period. Since then, it has welcomed travelers seeking a peaceful retreat deep in the mountains and has become known as one of Minakami’s historic hidden hot springs.
Hoshi-no-Yu: A Historic Bathhouse from 1895
One of the most famous features of Hoshi Onsen is Hoshi-no-Yu, the large communal bathhouse built in 1895. The wooden building combines traditional Japanese architecture with Western-inspired elements reminiscent of the Rokumeikan era.
The large semicircular windows and massive log beams create an impressive atmosphere, while the building continues to preserve the character of the original bathhouse more than a century after its construction.
The floor of the bathing area is covered with smooth river stones. Hot spring water naturally rises through the gaps between the stones and fills the baths from below. This unusual design allows bathers to experience the spring water almost exactly as it emerges from the source.
There are four bathing pools, each with a slightly different temperature, allowing guests to choose the bath that feels most comfortable.
A Favorite Retreat of Writers and Literary Figures
Hoshi Onsen has long been loved by prominent Japanese writers and literary figures, including Tekkan Yosano, Akiko Yosano, Bokusui Wakayama, and Yasunari Kawabata. Their writings and memorabilia are displayed throughout the inn, adding to the sense of history and literary atmosphere.
The inn is also famous as the setting for a classic Japanese National Railways “Full Moon” advertising campaign. A photograph of actors Ken Uehara and Mieko Takamine bathing at Hoshi Onsen became widely known throughout Japan and helped introduce the secluded hot spring to a much broader audience.
The Historic Charm of Hoshi Onsen Chojukan
Today, Chojukan is the only inn operating at Hoshi Onsen. The property consists of several buildings, including the Main Building, Annex, Kunzan-so, and Horyuden.
The Main Building, Annex, and Hoshi-no-Yu bathhouse are all registered as Tangible Cultural Properties of Japan, making the inn an important example of historic hot spring architecture.
The entrance hall features a high ceiling with beautifully aged, dark wooden pillars and beams. A traditional irori hearth beside the entrance is another symbol of the inn. The gentle crackling of firewood creates a welcoming atmosphere where travelers can naturally gather and exchange stories.
Three Main Bathing Areas
Hoshi-no-Yu
Hoshi-no-Yu is the inn’s famous large communal bath. It is a mixed-gender bath, with a women-only bathing period from 8:00 p.m. to 10:00 p.m.
Because the spring water rises naturally through the stone floor of the bath, bathing here offers a rare opportunity to experience the hot spring in an exceptionally authentic setting.
Chojuno-Yu
Chojuno-Yu is a women-only bath designed for a quiet and relaxing bathing experience. It has also received high evaluations from the Japan Natural Hot Spring Examination Organization.
Tamaki-no-Yu
Tamaki-no-Yu is a bathhouse constructed primarily from Japanese cypress. It features both an indoor bath and an open-air bath and is available to men and women on alternating time schedules.
With its relatively modern facilities, Tamaki-no-Yu is also a comfortable choice for visitors experiencing Hoshi Onsen for the first time.
A Stay in Harmony with Nature
The guest rooms are located along the Hoshi River, allowing guests to relax while listening to the gentle sound of flowing water.
Dinner features locally sourced ingredients such as Joshu Beef and Joshu Barley Pork, offering flavorful cuisine inspired by the mountain villages of Gunma.
The scenery changes dramatically with the seasons. Fresh greenery arrives in spring, lush forests surround the inn in summer, colorful foliage covers the mountains in autumn, and snow transforms the area into a quiet winter landscape.
Staying at Hoshi Onsen offers a chance to step away from everyday life and enjoy a peaceful atmosphere where traditional architecture, hot spring culture, and mountain nature come together.
Day-Use Bathing and Visitor Information
In addition to overnight stays, day-use bathing is currently available at Hoshi Onsen. Day visitors can use Hoshi-no-Yu and Chojuno-Yu. The facility is closed on Wednesdays.
Day-use bathing reception is available from 10:30 a.m. to 1:30 p.m., with bathing available until 2:00 p.m. Because schedules and operating conditions may change, checking the latest information before visiting is recommended.
How to Get to Hoshi Onsen
By train, visitors can travel to Jomo-Kogen Station and continue by a Minakami Town-operated bus.
By car, Hoshi Onsen is approximately 40 minutes from the Tsukiyono Interchange on the Kan-Etsu Expressway.
After traveling along the mountain roads, the historic single inn of Hoshi Onsen appears quietly among the forests. Its secluded location and traditional atmosphere make it a true hidden hot spring retreat in the mountains of Gunma.
A Historic Hot Spring Preserving Japan’s Traditional Mountain Culture
With its rich natural surroundings, historic wooden architecture, and clear spring water rising naturally from underground, Hoshi Onsen is one of the most distinctive hot spring destinations in Minakami.
The combination of traditional toji culture, literary history, historic architecture, and seasonal mountain scenery offers visitors a glimpse of an older Japan, far removed from the bustle of modern cities.