This is the little brother to the XG-7. It was a compact, amateur-level camera meant to compete against Canon's AV-1. Like the others in the XG series, it takes all the Rokkor-X lenses, some dedicated flashes and an auto-winder.
I found a nice website on this camera series, The Rokkor Files.
This was another thrift-shop find. One of the nice things about it is that it came with an autowinder, a lens (albiet a 3rd party) and a neveready case that fits both the camera and the winder.