The Asama-Shirane Volcano Route (Onioshi-Manza Highway) is part of the Asama-Shirane-Shiga Sawayaka Highway, a limited-access road linking Nagano and Gunma prefectures through the Joshin’etsukogen National Park.
The Onioshi Highway is approximately 16 km in length and skirts the foot of Mt. Asama, linking Karuizawa in Nagano Prefecture with the Mihara district of Tsumagoi in Gunma Prefecture. Most of the route as far as Manza-Kazawaguchi consists of long straights, making it a well-known location for shooting promotional videos for cars.
The Manza Highway, meanwhile, is approximately 20 km long and runs along the base of Mt. Shirane, linking Tsumagoi with the hot spring resort of Manza in Gunma Prefecture. Much of it runs through wooded terrain, making it the ideal place to soak in the atmosphere of the forest. Drivers can enjoy refreshing breezes along the way as they pass through the many tree-shaded stretches that are cool even in summer.
From the fresh greenery of spring to the cool of summer, the colors of fall, and the snowy landscape of winter, this road linking tourist sites where drivers can enjoy all four seasons is included in the top 100 scenic drive selection of the Japanese motoring magazine Le Volant.