Shimanto River Ultra Marathon Online Challenge Japan 2026: 3-Month 100K

Shimanto River Ultra Marathon Online Challenge 3-Month 100K is the longest-duration 100 km round in the 2026 Shimanto virtual series. Participants accumulate the same 100 km target across October, November and December.

Three months to complete 100 km

Complete at least 100 km between 1 October and 31 December 2026 through TATTA. Multiple activities may be combined during the challenge period.

Participants must live in Japan and use the same RUNNET ID for registration and TATTA. Follow the official app-sync rules throughout the event period; this is a GPS-tracked virtual challenge, not a physical race.

Entry status

Registration ran from 2 August to 25 September 2026 and is closed. The activity window remains live through 31 December.

Packages and rewards

The same four published package tiers apply: JPY4,990, JPY6,990, JPY8,990 and JPY12,990. All include a T-shirt, with higher tiers offering combinations or choices of Shimanto regional foods and original event apparel. Verified finishers receive a finisher medal.

Credibility

RUNNET and the official Shimanto Ultra online-challenge site directly publish this category. It is a separate 3-Month round and not a duplicate of the November 1-Month or 2-Month Stage 2 events.