GBP/JPY is developing impulse subwave C (colored red in the chart) that is part of impulse wave C of larger degree - colored magenta in the chart. The latter is also part of wave C of still larger degree - colored royal blue in the chart.
The targets of the downmove are Fibonacci expansions off 139.93-132.90-137.03, 137.03-130.89-134.02, 134.02-131.79-133.15, 133.15-131.21-132.09.
Supports:
- 130.92-89 = confluence area of objective point (OP) and contracted objective point (COP)
- 130.23 = COP
- 130.15 = OP
- 130.00 = OP
- 129.54 = expanded objective point (XOP)
- 129.15 = .618 ret

Overbought/Oversold
Assuming that the medium term trend is down it's preferable to try short positions when the Detrended Oscillator gets above the zero level (50-55 pips above the current prices) or into the overbought area (90-105 pips above the current prices).
Read more on how to apply Fibonacci studies to calculate price targets.