Thanks for sharing those ideas, Janeo. I currently hold NKK Switches (TYO:6943), Sanko Sangyo (TYO:7922), Yotai Refractories (TYO:5357), Katsuragawa Electric (TYO:6416) and Fujix Ltd (TYO:3600).
Some other names I've been looking at recently: Kaneso (Nagoya:5979), Geomatec (Sapporo:2137), Somar (TYO:8152) and Nankai Plywood (TYO:7887).
Out of the three you mentioned, Kyowakogyosyo is most attractive to me at first glance.