It's about 8 miles. If you do it the wrong way, about 6.5 is uphill. One village is higher in elevation than the other.

The right way is to take the bus from the train station closest to Nagoya and (if you want to minimize the uphill part), get off at the upper parking lot/end of the line. We found this village to be way more touristy than the "Quirky Japan Web Page" led us to believe, although it is a pedestrian walkway. At the other end (Magome?), you have to take a taxi to the train station for about Y1500. Trains do not run very often on this route, so plan ahead.