If you're not quite up for the Tokyo Marathon but still want to walk or run through the city at your own pace and for a good cause, the annual Tokyo Yamathon fundraiser is the event for you. First held in 2010, the Yamathon has been steadily growing in stature, with an expected 1,000 participants this year. All registration fees and donations go directly to Plan Japan, a UN-recognised nonprofit that's currently working on rebuilding elementary schools in the parts of the Philippines affected by Typhoon Haiyan in 2013. Following this course or any other route of their choosing, walkers and runners alike must visit all 29 Yamanote line stations within 12 hours and take a photo of their team (3-4 members) in front of each one to complete the Yamathon. Alternatively, you can choose to do the half Yamathon, a new addition for 2016 that runs from Tokyo Station to Mejiro Station. Registration costs ¥10,000 per team and must be completed both in advance (by May 10) and on the day.
The Yamathon organisers are also looking for volunteers to help out with practical arrangements and the like – check out the event website for details.