It is an excellent lens, no matter who made it though.
If it's anywhere near as good as it's slower sibling, the Auto Rikenon EE 50mm f/1.7 (made by Ricoh, I believe), you are not likely to be disappointed. That lens is a real winner.
People tend to get very hung up on the big Japanese brands of that era (Nikon, Canon, Minolta, Pentax & Olympus.... did I mention Nikon?) but the truth is that just about all of the optics coming out of Japan were extremely good and the less popular brands (Ricoh, Konica, Mamiya/Sekor, etc... as well as the optical contractors who put other names on their products (Tokina, Cosina, Sun, Komine, etc...) were very capable of making standout lenses.
All of these companies built different products to different price points so not every Japanese lens from that era is amazing but every one of those companies was
capable of making incredible optics and they all made examples that proved it. The Rikenon lenses are a perfect case in point.