Surprisingly good app
Watch out for site 12...to get to it from 11, Apple and Google Maps will route you to the other side of the mountain which doesn’t have access to the trail or a trail to get to the encampment. It’s better to skip 12, then go to 13 or 14 and then double back.
Recommendations for future content would be adding the other encampments and sites (there are a few more). I’d also recommend adding additional routes using the prefectural guide (in English and Japanese) to add additional walking tours.