Can you imagine yourself completing a 100-km mountain trail in 48 hours and — if this is not enough of a challenge — begging your family, friends and colleagues to part with some hard-earned cash and sponsor you? What's more, could you do all this voluntarily for the sake of a good cause? If so, welcome to the Oxfam Trailwalker and the world of charity challenges.

Fundraising based on physical activities such as walks, runs, bike rides or mountain treks have become popular in Japan in recent years. Participants raise money to support a nonprofit organization by collecting donations or pledges for completing a pre-determined course.

Walking a trail of 100 km from Odawara to Lake Yamanaka in the vicinity of Mount Fuji is a tough yet rewarding experience. This is the Japan Trailwalker, the latest regional twist on an event that started in Hong Kong. The original trail was based on a grueling military drill for Nepalese Gurkha soldiers posted to the former U.K. territory with the British Army. It is now a public fundraising event that has spread to Australia, the U.K. and New Zealand.