Main article: String of cash coins currency unit. Similar discounts existed probably for other bulk payments with small coinage in stringed form. Views Read Edit View history. The yen started to replace the old duodecimal denominations in in 3rd quarter of , the first new coins appeared, namely 5, 10, 50 sen silver and 2, 5, 10, 20 Yen. These coins would become the daily currency of the common people and would be used for small payments. See also: Tokugawa coinage.