Ultra Running Hub Semboku, Akita Pref., Japan · Sunday, September 27, 2026
Akita Nairiku 100km Marathon
Calculated from 100 km alone — the organiser has not published an elevation profile. Read 5.0 as a floor, not a verdict.
What the course asks
DUV results for the 2025 edition (100km) — finishers only. Starters are not published, so the field was at least this big and no finish rate can be given.
Typical conditions, September
Regional 2001-2020 average for September — NASA POWER, grid elevation 350 m. Not a forecast.
Results history
| Year | Race | Finishers | Men's winner | Women's winner |
|---|---|---|---|---|
| 2025 | 100km | 337 | Taku Fujiwara · 06:47:32 | Kaai Ichikawa · 08:13:38 |
| 2024 | 100km | 322 | Shun Masaoka · 06:53:11 | Kaai Ichikawa · 08:18:58 |
| 2023 | 100km | 497 | Shun Masaoka · 06:54:06 | Hisayo Kakinuma · 08:39:59 |
| 2022 | 100km | 360 | Hidekazu Tanaka · 07:15:28 | Kana Kobayashi · 08:21:47 |
| 2019 | 100km | 593 | Kouji Kayama · 07:26:09 | Tomoko Mitsuhashi · 08:32:39 |
| 2018 | 100km | 527 | Kouji Kayama · 07:35:03 | Reiko Akasaka · 08:54:15 |
| 2017 | 100km | 531 | Kouji Kayama · 07:21:44 | Reiko Akasaka · 08:47:36 |
| 2016 | 100km | 509 | Kouji Kayama · 07:21:42 | Reiko Akasaka · 08:46:12 |
| 2015 | 100km | 741 | Kouji Kayama · 07:20:21 | Tomoko Mitsuhashi · 08:52:59 |
| 2014 | 100km | 662 | Kouji Kayama · 07:15:15 | Asako Okoshi · 09:20:45 |
The field grew 5% between 2024 (322) and 2025 (337). 19% of the 2025 field were women.
DUV results for the 2025 edition (100km) — finishers only. Starters are not published, so the field was at least this big and no finish rate can be given.
Course notes
- gear With trail terrain, choose a shoe with moderate cushioning for optimal performance.
- nutrition For 100km+ efforts, prioritize real food at aid stations to prevent palate fatigue.
Gear for this race
Chosen for 100 km of trail.
- Trail Running Shoes 100 km of trail — cushioning that is still there in the last quarter.
- Race Nutrition Past 100 km the palate quits before the legs do — carry more than one flavour.
- Hydration Vests Flask capacity for 100 km, without the bounce.
- Headlamps A 13 h limit puts you out there after dark.
- Accessories Chafe and blisters end more 100 km races than fitness does.
Overview
Run on roads from Semboku, Akita Pref., Japan, the Akita Nairiku 100km Marathon featured a point-to-point route following the Akita Nairiku Jukan Railway. With 337 finishers in 2025, the race drew a field bigger than 91% of 100k events and smaller than 9%, placing participants in heavy company on the pavement.
A 13-hour time limit demanded an unrelenting tempo, tighter than 87% of 100k cut-offs and more generous than only 13%. That strict standard enforced a baseline pace of 7.8 minutes per kilometer from the start, leaving little room to falter over the full 100-kilometer crossing.
Similar races
Other 100K trail ultras, closest in distance first.