GBP/JPY is now moving within impulse wave C of long term downtrend - colored light green in the chart. Within this wave there are A and B subwaves with subwave B from 124.87 still developing (colored royal blue in the chart). The latter wave also has its subwaves - A , B and potential C colored red in the chart. Subwave РЎ is still developing from 126.63.
Now the targets of the upmove are Fibonacci retracements of 132.30-124.87, 130.82-124.87, and expansions off 124.87-128.11-126.63.
Resistances:
- 128.55-59-63 = confluence area of .618 and .50 retracements and contracted objective point (COP)
- 129.46 = .618 ret
- 129.87 = objective point (OP)
If the price reverses to the downside the immediate supports will be Fibonacci retracements of 124.87-128.11 and expansions off 139.93-130.26-135.11, 135.11-129.74-132.30, 132.30-128.19-130.82, 130.82-124.87-128.11, 128.11-126.63-127.84.
Supports:
- 126.93 = COP
- 126.49 = .50 ret
- 126.36 = OP
- 126.11 = .618 ret
- 125.45 = expanded objective point (XOP)
- 124.43 = COP

Overbought/Oversold
Assuming that the medium term trend is now up it's preferable to try long positions when the Detrended Oscillator gets below the zero level (current prices) or into the oversold area (10-20 pips below the current prices).
Read more on how to apply Fibonacci studies to calculate price targets.