Oku-Musashi Long Trail Race 105K & 35K

The 4th Okumusashi Long Trail Race takes place on Saturday, 30 May and Sunday, 31 May 2026 at Hannō City Central Park & Civic Hall in Saitama, Japan. This challenging trail running event offers four categories: Long 105K, Long 105K Pair, Short 35K, and Challenge 20K, traversing the Okumusashi mountains at elevations from 300m to 1,200m. Registration runs from 12 December 2025 to 15 April 2026 (or earlier if capacity is reached).

The Okumusashi region is where the Musashino Plateau rises westward into mountains ranging from 300m to 1,200m. This area has long been cherished by hikers from central Tokyo and is rich in natural beauty with green forests and clear streams. Historic sites include Mt. Bōnore, Mt. Izu, Shōmaru Pass, Taketora Temple, Konogenjin, Takayama Fudōson, and Kaore Pass, offering seasonal scenery throughout the year.

The Long 105K course accumulates over 8,000m of elevation gain—comparable to the height of Mount Everest—making it a truly challenging trail. The 35K and 20K courses were added to allow more people to enjoy trail running, with the 20K named "Challenge" as a first step toward longer distances. For the 4th edition, a 105K Pair category has been introduced specifically to encourage more female participation (Men+Women and Women+Women pairs; Men+Men not offered). Both members of a pair must arrive at each aid station and the finish simultaneously.

Official aid stations (cutoffs): Long 105K/Pair—A2 Haraba (27km) at 13:30 (7.5hr), A3 Nōra Naguri (41km) at 18:00 (12hr), A4 Naguri Genki Plaza (59km) at 3:00 (21hr), A5 Visitor Center (72km) at 8:00 (26hr), A6 Chōnenji (98km) at 16:00 (34hr), finish at 18:00 (36hr). Short 35K—A7 Hōkōji (15km) at 12:30/12:45 (4.5hr), A6 Chōnenji (28km) at 16:30/16:45 (8.5hr), finish at 18:00/18:15 (10hr). Challenge 20K—finish at 16:00 (6hr).

Mandatory gear for Long 105K/Pair: bib with timing chip, registered mobile phone with power bank, minimum 1.5L hydration, personal cup (no plastic bottles due to hygiene), course map downloaded, hooded rain jacket and pants (waterproof/breathable with taped seams), two headlamps (or one headlamp plus secondary light) with spare batteries, survival blanket (body-sized), IBUKI beacon (rental available at registration), reflective gear for night running, My Number ID card. For Short 35K and Challenge 20K: bib, registered mobile phone, minimum 1L hydration, personal cup, course map, hooded rain jacket, one headlamp, My Number ID card.

Recommended gear: cash for public transport in case of retirement, first aid kit, oral rehydration salts, sun protection, warm layers for nighttime temperature drops. Poles are permitted only for Long 105K/Pair starting from A2 (27km). Earphones (including bone conduction) and headphones are prohibited. Running barefoot is forbidden; sandals are not recommended but if used must be worn with socks.

Registration is via Runnet.jp from 12 December 2025 to 15 April 2026. Categories and capacities: Long 105K (400), Long 105K Pair (50 pairs/100), Short 35K (1,000), Challenge 20K (500). No category changes or cancellations due to personal circumstances. Refunds for event cancellation due to earthquakes, weather, or other factors are at the organizer's discretion.

Participant perks: All finishers receive a finishing medal and participation award. The winners of Long 105K (one man, one woman) will be invited to Chiang Mai by UTMB 2026 in Thailand, including 4 nights/5 days accommodation and race support (travel expenses not included). ITRA points: Long 105K/Pair 5 points, Short 35K 2 points, Challenge 20K 1 point. UTMB Index: Long 105K (100M), Short 35K (50K), Challenge 20K (20K).

Check-in dates: Long 105K/Pair only on 29 May 15:00–20:00 (mandatory gear check). Short 35K: 29 May 15:00–20:00 or 31 May 06:00–07:30 (first 400 who selected day-of check-in). Challenge 20K: 30 May 06:30–09:00 only. Start order for Long 105K and Pair: based on ITRA Performance Index, 2024/2025 race records, or predicted time. Short 35K: wave start (A at 8:00, B at 8:15) based on same criteria, maximum 500 per wave.

Awards: Top 6 overall men and women in Long 105K, Short 35K, and Challenge 20K. Age categories (18-39, 40s, 50s, 60s, 70+) top 3 men and women. Pair categories: top 3 for Men+Women pairs and top 3 for Women+Women pairs. Overall awards take priority.

Disqualification applies for littering, leaving designated course, disobeying staff instructions, missing cutoffs, age/gender misrepresentation, running under another name, not wearing bib, lacking mandatory gear, or poor sportsmanship.

The Okumusashi Long Trail Race is organized by the Okumusashi Trail Running Association, chaired by Hiroshi Hiranuma, with event management by the Okumusashi Long Trail Race Executive Committee. Cooperating organizations include NPO Okumusashi Green Resort, Himawari Sanso, and BeeeBee. Supported by Hannō City, Hannō City Board of Education, Hannō Chamber of Commerce, Hannō Tourism Association, Hannō Sports Association, Hannō Neighborhood Association Federation, Seibu Railway (planned), and others.

The official race song "Rikishō" (Power Run) by singer-songwriter Nagaharu Onuki is available as a CD add-on option for 800 yen per entry. The song is performed live at the opening ceremony and serves as the main theme of the event.

The Okumusashi Long Trail Race invites runners to discover the green mountains and clear streams of Okumusashi—a region once thriving with forestry and hikers, now revitalized through trail running. Whether you are chasing ITRA points, UTMB Index, a 105K pair challenge, or your first 20K in the mountains, this course offers a rewarding and unforgettable experience. Register before 15 April 2026 to secure your place.