21st Shonan International Marathon 2026

The 21st Shonan International Marathon returns to Kanagawa's Shonan coast on Sunday 6 December 2026, with the Oiso Prince Hotel as the event venue. It is one of Japan's largest mass-participation road-running events, with roughly 26,000 places across the full programme. The headline marathon starts near the Seisho Bypass Oiso Nishi IC and follows a coastal out-and-back route through Hiratsuka and Chigasaki towards the Enoshima area before returning west, using a second turnaround near Seisho Ninomiya IC and finishing at Oiso Prince Hotel.

The marathon's defining operational feature is its "My Bottle" format. Full-marathon runners must start carrying at least 200 ml of fluid in their own bottle, while 10K runners must carry their own cup. The organiser provides frequent refill points along the course rather than disposable cups and plastic bottles. This sustainability model is now entering its fifth year and the organiser reports a major reduction in event waste compared with conventional race operations.

The full marathon starts at 09:00 JST and has a 6 hour 30 minute finish limit, with nine intermediate course cut-offs. The 10K fun run starts at 09:50 with a two-hour limit. The programme also includes 2K races for junior-high students, upper-primary students and parent-child pairs, plus an inclusive 1.4K Run & Walk that accommodates eligible participants with disabilities, accompanying guides, wheelchairs and certain stroller participants under the published rules.

Registration opened on 4 April 2026 on a first-come, first-served basis and all categories are now closed. Overseas residents were eligible for the full marathon through the dedicated RunJapan pathway. The current regulations state there is no general pre-race athlete reception: number cards and timing tags are sent in advance to registered participants, and the marathon and 10K use chip timing with official results based on net time. International entrants should follow the overseas registration instructions for any delivery arrangements that differ from domestic entry.

Public transport is strongly recommended because private cars and motorcycles are not permitted at the event venue on race day. The organiser also publishes direct-bus and accommodation transport options for runners travelling to Oiso.