The Japanese Yen can be a lucrative market to trade. The market is heavily traded at the IMM Division of Chicago Mercantile Exchange.
Open interest is large, and daily volume is high.
Sometimes, depending on overnight fundamental news, or technical events, the market may open dramatically lower or higher. For example, the market may close at 72.50 but open at 71.30 the next trading day on the floor of the CME in Chicago. Still another problem with the Yen is on occasion the market has a powerful move, much greater than normal. Another possibility is placing overnight stops in the EFP market in order to prevent the gaps from going against you. These are very useful tools in helping to trade all of the currencies.