44th Koto Seaside Marathon Tokyo 2026

The 44th Koto Seaside Marathon takes place on Sunday 29 November 2026 in Tokyo's waterfront Koto ward. Its long-running autumn programme features a Japanese athletics federation-certified half marathon and 10 km race, both starting and finishing at Yumenoshima Athletics Stadium. The organisers offer 4,000 places, split between 2,400 half-marathon runners and 1,600 10K runners. The setting gives participants a chance to explore Tokyo's reclaimed coastal districts rather than the usual central-city tourist route.

The half marathon starts at 9:15 am and the 10K at 9:45 am, with a formal opening ceremony at 8:40 am. Runners must finish within 2 hours 30 minutes for the half and 75 minutes for 10K. The course uses kilometre markers and staged cutoff points; the half marathon's 5 km, 10 km, 15 km and 20 km intermediate restrictions are particularly important for entrants pacing towards the overall limit. The event has general and masters divisions, the latter for runners aged 50 and over on race day.

The organising committee includes Koto City, its sports bodies and the local athletics association. Entrants must have been at least 16 years old on 1 April 2026. Registration closed 31 July, with oversubscribed places allocated by ballot and preference for Koto residents. Fees varied by residence and race distance. All participants receive a commemorative event T-shirt, while finishers can obtain a printed result certificate on race day or an online copy. The race also participates in a programme offering qualifying runners an opportunity to secure Tokyo Marathon 2028 places under specific published conditions.

Athlete bibs and timing tags are sent in advance, so there is no race-morning registration. The venue is about a five-minute walk from Shin-Kiba Station, served by the Keiyo, Yurakucho and Rinkai lines. Event organisers advise against driving because there is no nearby race parking. Check official race communications for route restrictions and weather notices.