Hasetsune Cup

The Japan Mountain Endurance Race is one of the country's defining trail ultras. A field of roughly two thousand leaves western Tokyo in the early afternoon, carrying mandatory navigation and safety gear into a long night on the Okutama ridgeline. The 24-hour limit is generous for the leaders but serious for runners managing darkness and limited aid.

The 71.5 km route starts and finishes in Akiruno and crosses a chain of Okutama summits, including Mito, Gozen, and Odake. The course gains about 4,582 meters, has long technical ridge sections, and provides very little water. Darkness is part of the intended challenge rather than an exception.

Autumn conditions can change quickly across the Okutama mountains. The start may feel mild, but exposed ridges and overnight sections can turn cold, wet, and windy, so layers and lighting matter as much as early pacing.