Yen, the unit of value and account in Japan, its value being 48.5 cents in American money. Japan mints the following coins in gold (besides the silver yen): 1, 2, 5, 10 and 20 yen pieces — the value of the 10-yen piece being $4.85; and of the 20-yen piece $9.70, the rough equivalent of our $5 and $10 gold coins.