Four- and one-mon copper coins were also legally equivalent to two-rin ("Rin," a monetary unit equivalent to one-thousandth of one yen) and a one-rin coin, respectively, until 1953.
昭和28年（1953年）まで、銅貨4文銭は2厘、銅貨1文銭は1厘硬貨として法的に通用していた.