The Japanese Yen was weaker at the start of yesterday's trade due to the downgrade warning because of growing Japanese debt. However, when the EUR started to decline after the Greek deficit was released by the European Union, investors responded by moving back to safe heaven currencies such as the Yen and the USD. The EUR/JPY pair was lower at the end of yesterday's trading, currently at 123.51, and the GBP/JPY was down slightly and currently trading at 143.34.
As long as the Greek debt issue continues to occupy investors, the trend will continue to support the JPY against the EUR and against the GBP. The JPY might however be less bullish against the USD. Expectations for the USD/JPY pair would reach 100 because the U.S. economy seems stronger while the Japanese economy is still experiencing deflation.