The EUR/JPY pair is an important currency pair, often watched closely as a barometer of risk-on activity. The more that the pair is bid up, the more that the market is thought to be signaling risk-on activity. The reverse is true: when the euro weakens against the yen, a risk-off signal is offered, which typically translates into weakness among risk assets such as U.S. equities.
The chart below demonstrates this; the daily candlesticks present EUR/JPY price action, and the purple line illustrates how S&P 500 futures have traded with positive correlation to the same currency