The tweet I have made a minute ago seems to be misleading. It was popularly accepted just a year ago or so that JPY 100 was equivalent to one USD in terms of PPP. The value most of the Japanese feel comfortable about. Japanese Yen began its history in 1871. Japan issued a new currency ordinance stipulating a shift from "Ryou" to "Yen". One JPY was one USD, meaning one silver coin of JPY was equivalent to one silver coin of USD. After the end of the Greater Asia War, JPY was fixed at 360 Yen per one USD under the Bretton woods system. However, it is now trading at 76.669 per USD.