Ecomarathon de Saïko de Décembre

The Ecomarathon de Saïko de Décembre takes place on 27 December 2026 in Toda, Saitama Prefecture, Japan, beside Saiko lake in Doman Green Park. The half marathon and the 10 km start at 11am, both run as loops around the park's ponds and green spaces. A 5 km parent-and-child race, also on a loop, is on offer for families.

The race is part of a series of Ecomarathon events held across several Japanese prefectures in support of charitable causes: participants can, for example, donate to Second Harvest Japan, the country's first food bank.