Korean currency
The yen was the currency of Korea during the Colonial rule, from 1910 to 1945, and was issued by the Bank of Joseon It was equivalent to the Japanese yen and consisted of Japanese currency and banknotes issued specifically for Korea. It was replaced by the South Korean won at par in 1945, and by the North Korean won in 1947.
List of licensed and localized editions of Monopoly: Africa and Asia
The currency used in the game is shown with the letter "M" crossed by two horizontal lines. This is not the real currency of the Republic of Korea.