The Ecomarathon de Saiko de Decembre begins next to Sai Lake in Doman Green Park, Toda, Saitama, Japan. This late-December road race offers 10 km and half marathon distances, alongside a 5 km parent-child race suitable for families. The start time is 11:00 AM, providing a relaxed daytime atmosphere instead of an early morning start.
The 10 km and half marathon courses are loops, as is the 5 km family race. The route winds around lakes, ponds, and parkland, giving the impression of a run through green space rather than an urban setting. The eco-marathon designation aligns with its commitment to the environment, and the combination of individual distances with a parent-child option serves both regular runners and families participating in a short race together.