Japanese commemorative gift yunomi with box, dated 1961

This yunomi is 3.5" high with tomobako. The tomobako appears to be hand signed. There is nothing very refined about this cup, it is very rustic. The molding, writing and design on the cup are very roughly done and someone has added some sort of padding to the bottom, maybe cork. The writing on the bottom is completely illegible and the cup is a bit asymmetrical, organic and earthy in color. Someone was proud enough of it to box it, though. Uncertain of the style or age. Another research opportunity.

Thanks to wma for providing some translation of the writing! (1961, commemorative gift)

After some research, I think this may be Okinawan, possibly Koza or Tsuboya Yaki. I have found some very similar work by them.