20 Sen Uniface pattern

Japanese pattern coins of the Meiji period were frequently produced as internal proposals submitted to the mint's own design committee or to foreign advisory engravers, and many never progressed beyond a single presentation striking. Uniface patterns — struck on only one die with the reverse left blank — were a standard proofing technique used at the Osaka Mint during the 1870s and 1880s to evaluate obverse or reverse designs in isolation before committing to a full working die pair.

The 4.50g weight aligns with the silver 20 sen standard established under the New Currency Act of 1871, which pegged Japanese coinage to a decimal system modeled partly on the U.S. dollar structure.