Okinawa 100K Ultramarathon by TATTA Online Challenge Japan 2026

Okinawa 100K Ultramarathon by TATTA is a two-week virtual running challenge supported by the Okinawa ultra's organising committee and organised by R-bies Sports Foundation. Participants run on their own routes. It is separate from both the physical Okinawa 100K race and the February 2027 Okinawa Online Marathon.

Accumulate your distance in December

Complete your selected 50 km, 100 km or 200 km total during 14-27 December 2026. There is no limit on the number of sessions used to reach the target. These are accumulated challenge distances, not a requirement to run a continuous ultra.

Register in your own name and use the same RUNNET account with TATTA. Check that the event appears in the app after payment. Only Running and Trail Run activities qualify; Walking, Hiking and Cycling do not. Treadmill recordings are excluded, and manual distance entry is generally not accepted.

Set up any compatible GPS-watch connection before running. The official FAQ requires activity data to reach TATTA before 23:59 Japan time on 27 December. Do not leave synchronisation until the final minute. Activities crossing the opening or closing date boundary are excluded. The event requires activity and training-ranking visibility; the registration instructions separately recommend keeping activity maps private or visible only to friends.

Eligibility and entry choices

Entrants must live in Japan and be at least 18 years old. High-school students are excluded, even when aged 18. The published capacity is 2,000, and registration may close early if places fill. The scheduled final deadline is 7 December at 23:59 Japan time.

The four package options are alternatives for each distance. Choose the package and any shirt size carefully because changes after entry are not accepted. Only the all-items package includes the shirt and both food options together. Finisher medals are conditional on verified completion, not automatic gifts for entering.

Practical information

There are no competitive awards, shared aid stations or physical-race services. Participant insurance is not included. Domestic dispatch timing and arrangements for perishable food should be confirmed with the event office.

For this challenge, contact okinawa@runners.co.jp or +81 98-943-6644. Do not use another R-bies event's contact details.