Fed Interest Rate Decision is announced in 2014-07-30 (this week) BoJ Interest Rate Decision is announced in 2014-08-07 (next week).
If Fed rises the interest rates it is positive, or bullish, for the USD. If Fed keeps the ongoing interest rate it is negative, or bearish.
If BoJ rises the interest rates it is positive, or bullish, for the JPY. If BoJ keeps the ongoing interest rate it is negative, or bearish.
So possible scenarios: Fed's action; BoJ's action; Outcome 1. Rise Rise ? 2. Keep Keep ? 3. Rise Keep USDJPY up 4. Keep Rise USDJPY down
Which one is going to be? As looking in trading activity Sydney and Tokyo last hours are in favour of JPY, today I expect London will bee neutral and New York should support USD.