GBP/JPY is still moving within impulse wave C of long term uptrend - colored light green in the chart. On smaller scale this wave has the following subwaves: impulse subwave C (colored royal blue in the chart) that may be over at 135.11 - where wave C of still smaller degree ended (colored magenta in the chart). Now we have a correction and the immediate supports are Fibonacci retracements of 131.25-135.11, and expansions off 135.11-133.45-134.16.
Supports:
- 133.18-13 = confluence area of .50 retracement and contracted objective point (COP)
- 132.72 = .618 ret
- 132.50 = objective point (OP)
If the price reverses up the immediate resistances will be Fibonacci retracements of 137.03-130.26, 139.93-130.26, and expansions off 130.26-133.16-130.74, 130.74-132.96-131.25, 131.25-133.78-132.61, 132.61-135.11-133.45.
Resistances:
- 134.99 = COP
- 135.10-14 = confluence area of .50 ret and (OP)
- 135.43 = expanded objective point (XOP)

Overbought/Oversold
Assuming that the medium term trend is up it's preferable to try longs when the Detrended Oscillator gets below the zero level (current prices) or into the oversold area (15-30 pips below the current prices).
Read more on how to apply Fibonacci studies to calculate price targets.