The trail was only about 8km as the red-crowned crane flies but with the ups and downs it was about twice that. It was great fun - winding paths through the hills, thick bamboo forests, the never-melting snow, passing ancient castles, male and female waterfalls, and lots of great views of the mountains.
Japan's really has beautiful countryside and it is quite a revelation to be out of the cities: no concrete, no neon, just lovely houses and amazing landscapes. People say it's the 'real' Japan and I'm minded to agree.
We even found Joanna Lumley's walking stick.
(Thank you Toby for the fabulous suggest of this part of our trip.)