Near “Guidepost 8/22”, after passing the Ichirizuka milestone, you will see the characters for Enshū (“遠州”), written on a stone. The writing is faded and hard to make out, so a lot of people pass this stone without noticing it.
Enshū is the former name of modern-day Shizuoka Prefecture. Travelers may have rested here as they traveled the Magose-toge Pass from Shizuoka through to the Kumano Sanzan, the Three Grand Shrines of Kumano.
We don’t know the purpose of engraving these characters, but even after 200 years of being walked over by travelers, the fact that they are still visible means the carving must have been pretty deep. It could have taken more than half a day to do. It’s really interesting to think about who might have carved this and the purpose behind it.