Okinoshima 100km Ultra Marathon

Race completed

100 km Distance

not publishedn/a Climbing

5.0 est Grit · Challenging

Calculated from 100 km alone — the organiser has not published an elevation profile. Read 5.0 as a floor, not a verdict.

36.2135° N, 133.3115° E © OpenFreeMap © OpenMapTiles Data from OpenStreetMap

What the course asks

Time limit 14 hours 8:24 min/km average. Tight. Sustained running. Long aid-station stops will cost you. Climbing is unpublished, so this pace is a ceiling on the effort, not a measure of it. Tighter than 81% of 100K races. Measured against 226 races of the same distance. Cut-off calculator →

Field size ~317 Large. Rarely out of sight of another runner.

DUV results for the 2026 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, June

Daytime high 22°C

Night low 20°C

Rainfall Showers likely

Daylight 14 h 38 m of light

Regional 2001-2020 average for June — NASA POWER, grid elevation 10 m. Not a forecast.

Results history

Year	Race	Finishers	Men's winner	Women's winner
2026	100km	317	Kouki Katsube · 07:55:25	Risa Shinozaki · 08:50:36
2025	100km	286	Yuichi Aikawa · 08:08:30	Risa Shinozaki · 08:44:10
2024	100km	302	Yuichi Aikawa · 07:46:57	Risa Shinozaki · 08:44:46
2023	100km	275	Yuichi Aikawa · 08:01:10	Risa Shinozaki · 08:29:21
2022	100km	202	Ryuta Yoshida · 07:40:07	Risa Shinozaki · 09:03:00
2019	100km (Partial)	469	Nariaki Okawara · 07:39:52	Risa Shinozaki · 08:45:31
2018	100km	446	Nariaki Okawara · 07:47:41	Risa Shinozaki · 09:03:15
2017	100km	403	Yoshiki Kawauchi · 07:29:05	Shiho Shiomi · 09:03:39
2016	100km	434	Yoshiki Kawauchi · 07:20:29	Shiho Shiomi · 09:22:16
2015	100km	491	Takuya Nakamura · 07:33:30	Tomoko Yuunaga · 09:01:22

The field grew 11% between 2025 (286) and 2026 (317). 21% of the 2026 field were women.

DUV results for the 2026 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 road 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 road.

Trail Running Shoes 100 km of road — 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 14 h limit puts you out there after dark.
Accessories Chafe and blisters end more 100 km races than fitness does.