The ISO 4217 code for the Japanese yen is JPY. The three-letter code combines Japan’s two-letter country identifier, JP, with Y, the initial of yen.
ISO 4217 is the international standard used to identify currencies in banking, payments, accounting and foreign-exchange trading. Japan’s numeric currency code is 392, and the yen has a standard minor-unit value of zero: unlike many currencies, it is not normally represented as being divided into hundredths for everyday monetary calculations.
The alternatives are easy to misread. YEN is an English word for the currency, but it is not the ISO code. JPN is a three-letter country code used in some systems, not Japan’s currency identifier, and JNY is simply not the assigned code. The yen symbol is ¥, while Japanese prices may also use 円 in Japanese writing.