GBP/JPY is developing corrective wave against 135.1-130.47 - colored royal blue in the chart. According to wave count this can be wave B of medium term downtrend. The targets above the current level are Fibonacci retracements of 135.11-130.47.
Resistances:
- 132.24 = .382 retracement
- 132.79 = .50 ret
- 133.34 = .618 ret
If the downtrend resumes and the price breaks below 130.47 the immediate supports will be Fibonacci retracements of 122.49-139.93, and expansions off 139.93-130.26-135.11, 135.11-130.63-132.27
Supports:
- 129.50 = contracted objective point (COP)
- 129.15-13 = confluence area of .618 retracement and COP
- 127.79 = objective point (OP)

Overbought/Oversold
Assuming that the medium term trend is down it's preferable to try shorts when the Detrended Oscillator gets above the zero level (current prices) or into the overbought area (15-25 pips above the current prices).
Read more on how to apply Fibonacci studies to calculate price targets.