Lake Saroma 100K Online Challenge Japan 2026: Two-Month Stage 2

Lake Saroma's online challenge lets runners build a 100 km total on their own routes while sharing the identity of the Hokkaido ultramarathon. This listing is specifically the two-month Stage 2 running from November through December, not the separate one-month rounds or the physical Lake Saroma race.

Completing the distance

Accumulate at least 100 km between 1 November and 31 December 2026. Multiple runs count towards the target; this is not a requirement to complete a continuous 100 km ultramarathon.

Use TATTA with the same RUNNET account used for entry. Only activities labelled Running or Trail Run qualify. Walking, Hiking and Cycling are excluded, and manually entered distances are generally not accepted. Set up any compatible GPS-watch connection before starting, check that the event appears in TATTA after payment, and synchronise eligible activities before the challenge ends.

Activities crossing the opening or closing date boundary are not counted. Test recording in advance and retain your original activity evidence.

Eligibility and registration

The event is restricted to residents of Japan with a smartphone capable of using TATTA. No age limit is stated for the four packages, although RUNNET restricts the payment methods available to under-18 applicants. Each participant must enter using their own account; proxy family/group entry is not supported.

Registration closes on 27 October at 23:59 Japan time, or earlier if capacity is reached. Select the clothing style, colour, size and any package extras carefully because changes after registration are not allowed.

What this virtual entry does not provide

Completion does not count towards Saroman Blue status in the physical ultramarathon. No access to its physical course, aid stations or on-site services is included. Participants are responsible for arranging their own insurance.

For this online challenge, use the event office at tatta-campaign@runners.co.jp. The published support notice says the office is closed from 26 December to 3 January, so resolve tracking or delivery questions before that period where possible.