Yes, it's a ropeway, called a yaen 野猿, which means "wild monkey", named for the resemblance to a monkey climbing along a rope.

Ropeways similar to this were in use into the late 19th century:

• http://libweb.hawaii.edu/libdept/asia/books/japan/106JPG.htm

and traditional-style yaen of more substantial construction are still in use:

• https://www.youtube.com/watch?v=pdMSvBdoRQs

There are a few different ways in which traditional yaen were powered. Your Musashi example appears to have ropes tied to it leading to each side, which will be pulled by a human (or possibly horse) on each side, or at least uphill, with the downhill journey powered by gravity. The two examples I linked above are powered by the rider - the first just pulling the gondola along using the main support rope, and the second using a dedicated rope for pulling (which can be thinner, and can be pulled while staying within the closed gondola).