I was able to finally remove one of my lone sole cards and match it to this new set that I picked up. This is the 1937 Rikishi Left Box 5 set (Catalog # R3711). It has one of Yokozuna Minanogawa's first Yokozuna menko in it and Shinkai's last menko as well. It also contains a rare gyoji card. Each menko measure about 1.0" x 2.25" and has some pretty cool gold gilding on the front. Unfortunately some ambitious kid wrote on the back of them, but it definitely gives them character.