The rules around mandatory equipment are posted here:
https://www.ultratrailmtfuji.com/en/about/rules/Starting with this year’s race, course maps downloaded onto a smartphone are no longer allowed. This is because of problems that have occurred with the phone running out of batteries as well as difficulties viewing the digital maps.
All runners must print out and carry with them during the race, a paper copy of the detailed course maps. The numbers written on the detailed course maps are used during emergencies to help us identify your location.
[Attention] Please put the maps in a clear plastic bag to avoid getting them wet when it rains.
The detailed course maps can be downloaded and printed out from the following link: