Niigata Pref., Japan · Sunday, September 27, 2026

Fixed Distance 100K

Aga Ultra Marathon - 100km

24 days to go

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.

What the course asks

Time limit 10.5 hours 6:18 min/km average. Tight. You are racing the clock from the start. Climbing is unpublished, so this pace is a ceiling on the effort, not a measure of it. Among the tightest 100K cut-offs we track. Measured against 203 races of the same distance. Cut-off calculator →

Field size ~28 Small. Long stretches with nobody in sight.

DUV results for the 2025 edition (105km) — finishers only. Starters are not published, so the field was at least this big and no finish rate can be given.

Typical conditions, September

Daylight 12 h 01 m of light

The Aid Station

Course-specific beta from the community

👟 gear

With trail terrain, choose a shoe with moderate cushioning for optimal performance.

By UltraHub Expert

🥤 nutrition

For 100km+ efforts, prioritize real food at aid stations to prevent palate fatigue.

By UltraHub Expert

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 100 km almost certainly means running into the night.
Accessories Chafe and blisters end more 100 km races than fitness does.