1 Sen - Shōwa Not issued

Produced in the final months of the Pacific War as Japan's metal supplies had been almost entirely redirected to military production, this red porcelain trial piece was part of a series of emergency material experiments that also included clay and other ceramic compositions. The issue was never authorized for circulation — Japan's surrender in August 1945 rendered the entire program obsolete before distribution could begin.

Surviving examples exist almost exclusively in institutional and specialist collections, having never passed through public hands in any commercial sense.