Usui Pass, Mountain pass between Nagano and Gunma Prefecture, Japan

Usui Pass is a mountain crossing between Nagano and Gunma prefectures that sits at an elevation of 956 meters (3136 feet) and links the resort area of Karuizawa with the Kanto plain. The road winds through forested slopes with curves that define the character of the route and open views across the surrounding landscape.

The crossing was part of the ancient Tosando road system that carried travelers between regions for centuries. It appears in the Nihon Shoki chronicles in connection with the legend of Yamato Takeru, who traversed the area on a mythical journey.

Kumano Kotai Shrine (Kumano Kotai-jinja) stands at the pass summit, and its bell inscription of 1292 (Shōō 5) indicates the road through this point was open by then. The shrine is also called Usui Tōge Kumano-jinja, and the old Nakasendō route passed it.

The old National Route 18 over the pass, about 11 km long, was closed for several months as of 2024 after a landslip between Karuizawa and Kumadaira. The bypass and the Joshinetsu Expressway offer faster, safer crossings. The old Nakasendo route is maintained as a hiking course.

The old National Route 18 through the pass has 184 curves over about 11 km, more than the Nürburgring's 172 over roughly 20 km. The road appears in the manga Initial D as the home course of Team Impact Blue, and drift racer Keiichi Tsuchiya has used it for tyre testing.