A Refreshing Route with Close-Up Views of Mount Asama
One of the greatest attractions of Onioshidashi Highway is its impressive views of Mount Asama. The Karuizawa-side starting point, Minenochaya, is located at approximately 1,655 meters above sea level and is the highest point on the route.
From there, the highway gradually descends toward Tsumagoi, providing a comfortable mountain drive with constantly changing scenery.
On clear days, travelers can see Mount Asama and Mount Koasama nearby, while more distant mountain ranges include Mount Kusatsu-Shirane, Mount Manza, and Mount Azumaya.
The section between Minenochaya and Onioshidashi Park is particularly impressive. Driving with Mount Asama rising alongside the road creates a strong sense of being immersed in the mountain landscape.
Onioshidashi Park and a Landscape of Ancient Lava
The name of the highway comes from Onioshidashi Park, a vast volcanic landscape created by the enormous eruption of Mount Asama in 1783.
The eruption produced a lava flow approximately 3 kilometers wide and 12 kilometers long. The resulting field of dark, jagged lava rocks forms a dramatic landscape that looks almost otherworldly.
There are relatively few tall trees around Onioshidashi Park, allowing the landscape to open dramatically in all directions. Visitors can enjoy expansive panoramic views of Mount Asama rising behind the black lava fields.
The area offers an opportunity to see both the destructive power of a volcano and the gradual regeneration of nature. It is one of the most distinctive geological landscapes in the region.
Rokurigahara Rest Area and Views of Mount Asama
As travelers approach from the Karuizawa side, the scenery opens up around the Rokurigahara Rest Area. From here, Mount Asama can be viewed in its full scale, with its broad foothills stretching across the landscape.
The mountain changes dramatically with the seasons. Spring brings fresh green vegetation, summer offers cool highland air, autumn covers the surrounding forests in vivid colors, and winter creates a beautiful landscape of snow.
Summer is particularly pleasant because of the refreshing highland climate. Some sections of the highway feature long, straight stretches of road, which have also been used as locations for automobile promotional filming.
A Historic Japanese Motor Road
Onioshidashi Highway has an important place in the history of Japanese road transportation. It opened to traffic on August 1, 1933, and was one of the pioneering toll roads and motor-vehicle-only roads in Japan.
It was among the early examples of a purpose-built road designed for automobiles, during a period when modern motorization was still developing in Japan.
The diary of architect Ben Ikuta, who was active during that period, reportedly described the facility as a “modern barrier gate”, reflecting how innovative the road was considered at the time.
Today, the highway remains an interesting destination not only for its scenery but also for travelers interested in the history of transportation and Japan’s early automobile culture.
Route Information and Driving Guide
Onioshidashi Highway was developed by the Seibu Group and is currently operated as a toll road by Seibu Real Estate.
The approximately 16-kilometer route runs from Minenochaya Toll Gate, through the Onioshidashi area, to Kambara in Tsumagoi Village.
The toll is divided into two sections. For a standard passenger car, the Karuizawa section between Minenochaya and Onioshidashi costs ¥270, while the Kambara section between Onioshidashi and Kambara costs ¥370.
The road is open 24 hours and does not normally close for the winter season. However, temporary traffic restrictions may be introduced because of severe weather or volcanic activity around Mount Asama.
Because the road is restricted to motor vehicles, pedestrians, bicycles, mopeds of 50cc or less, and motorcycles of 125cc or less are not permitted.
A Scenic Route Through Joshin’etsukogen National Park
Onioshidashi Highway passes through the extensive mountain landscapes of Joshin’etsukogen National Park. The national park encompasses famous peaks such as Mount Tanigawa, Mount Naeba, Mount Kusatsu-Shirane, Mount Azumaya, and Mount Asama.
The combination of volcanic mountains, highland forests, open plateaus, and dramatic lava formations gives this part of Japan a distinctive natural character.
For travelers, the highway is more than a convenient connection between Karuizawa and Tsumagoi. The changing scenery itself becomes part of the journey.
Starting from the sophisticated highland resort atmosphere of Karuizawa, the landscape gradually changes into the rugged volcanic scenery and broad natural landscapes of Tsumagoi.
A Scenic Drive in Every Season
Onioshidashi Highway can be enjoyed throughout the year, with each season offering a different view.
In spring, snow gradually disappears from the mountains and fresh green leaves begin to emerge. Summer brings cool temperatures and refreshing mountain air.
In autumn, Japanese larch and broadleaf forests turn shades of gold, orange, and red. In winter, snow covers the surrounding mountains and forests, creating a striking white landscape.
The seasonal transformation of Mount Asama and the surrounding highlands is one of the defining attractions of the route.
The Asama-Shirane Volcano Route
Travelers who want to explore more of the region can continue from Onioshidashi Highway onto Manza Highway. Together, the two roads form the Asama-Shirane Volcano Route.
This extended journey takes visitors from the foothills of Mount Asama toward Mount Kusatsu-Shirane and onward to Manza Onsen, a famous high-altitude hot spring resort.
The route provides an excellent opportunity to experience the region’s volcanic geography, mountain forests, highland scenery, and hot spring culture in a single road trip.
A Memorable Mountain Road Trip in Japan
Onioshidashi Highway is an ideal destination for travelers who enjoy scenic driving, dramatic mountain landscapes, volcanic geology, and the freedom of exploring rural Japan by car.
With Mount Asama as its constant companion, the highway offers everything from expansive highland views and peaceful forests to the extraordinary lava fields of Onioshidashi Park.
For international visitors exploring Karuizawa, Gunma, or the northern Kanto region, a drive along Onioshidashi Highway can be a memorable way to experience a side of Japan far beyond its major urban centers.