OSJ ONTAKE50 2026

OSJ ONTAKE50 crosses the national forest at the base of sacred Mt. Ontake in Otaki Village, Nagano Prefecture. This event, part of the OSJ Trail Running Series, features two solo trail races: a Long course of approximately 54 km and a Middle course of approximately 30 km. Distances may vary based on forest road conditions. The Long race has a 10-hour time limit, and the Middle race has a 6 hour 30 minute limit. Entry is limited to 300 participants for the Long race and 200 for the Middle race. Healthy runners aged 15 and older may participate; parental consent is needed for those under 18. The course utilizes unpaved forest roads, typically closed to the public, which contributes to the race's distinct character. The majority of the route consists of runnable forest roads rather than narrow, technical trails, requiring runners to maintain a consistent, road-race-like pace while navigating mountain terrain. The Long course involves approximately 933 m of climbing and 963 m of descent. Otaki Village is situated below the 3,067 m Mt. Kiso Ontake and is heavily forested, with extensive national forest areas and notable cypress groves. Previously known as the Ontake Dirt Marathon, the race is held concurrently with the Self Discovery Adventure Dirt Run. The top 100 Long course finishers receive entry priority for the subsequent ONTAKE100.