Countermarked yen ("Gin")

Japan had officially switched to a bimetallic standard which made one yen silver coins legal tender throughout the country.

At least 20 million former Trade Dollars and 1 Yen coins were countermarked in 1897 with the character "Gin" for use in Korea, Lüshunkou, and Japanese-occupied Taiwan.

[4][5] The mark was put in place by the Japanese mints at Osaka and Tokyo to identify these coins as simply bullion.

[6] Countermarked yen are not considered damaged as the round "gin" mark meaning "silver" was officially placed by a government entity rather than by merchants (chopmarks).

[9] This applies less to "very rare" dates which will sell at a premium regardless of a "Gin" mark due to their low survival rates.