It's 22:47CET and Oanda is quoting EUR/JPY @ 135.45/59 and SaxoBank @ 135.21 There is an obvious arbitrage opportunite here. Too bad I don't have accounts in those brokers.
Saxo Bank is open for Forex trading: from Monday 06:00 Sydney local time (currently Sunday 20:00 GMT) to Friday 17:00 New York local time (currently Friday 21:00 GMT)
Try to calculate Your double spread paid for this "arbitrage opportunity" to Oanda and Saxo and maybe it will eat all possible profit ... And also try to examine time needed for You to enter such arbitrage trade on both accounts, it will be longer than arbitrage exists...