Shimanto River Ultra Marathon Online Challenge Japan 2026: October Run 1-Month 100K

Shimanto River Ultra Marathon's October Run 1-Month Online Challenge is a dedicated virtual 100 km round in the 2026 online programme. It is separate from the November and Year-end one-month rounds.

Accumulate 100 km during October

Complete at least 100 km between 1 and 31 October 2026 using TATTA. Multiple runs may be combined. Manual distance input is generally not accepted.

Participants must reside in Japan and have a smartphone capable of running TATTA. The same RUNNET ID should be used for registration and TATTA synchronisation.

Registration status

Registration ran from 2 August through 25 September 2026 and is closed. The event itself remains active through 31 October for runners who already entered.

Packages

All published courses include the original event T-shirt and an earned finisher medal. RUNNET/official event pricing is JPY4,990, JPY6,990, JPY8,990 or JPY12,990, with an additional 6% entry handling charge.

Higher tiers let entrants choose from Shimanto-region food products or event apparel. Examples include Shimanto udon or long-sleeve shirt at JPY6,990; bonito or selected apparel at JPY8,990; and Shimanto beef, eel or a four-piece apparel set at JPY12,990.

Credibility

The challenge is published on the official Shimanto River Ultra Marathon site and registered through RUNNET. R-bies Sports Foundation is the organiser and R-bies operates the programme. This provides a strong official organiser and registration chain.