The Nikkei 225 (NKD) peaked right at the end of the 2013, and proceeded lower until mid-May. June saw the price creep back higher, but that has stagnated. The Nikkei 225 had a false breakout higher in late July followed by a short-term lower low in early August - bearish signals.
Short trades can be taken near current levels of 15495, with a stop above 15660 and a target near 15000. Waiting for a drop below 15455, provides slightly more confirmation that the August rally is over, and still keeps the reward-to-risk ratio greater than 2:1 on the trade.
Figure 1. Nikkei 225 Stock Average Index Futures (NKD - September Contract)
The high on the September contract is 15810; if the price proceeds above that it has bullish implications, but given the choppy nature of the contract over the last several months buying breakouts at this juncture likely isn't the best play. Breakouts have been very short-lived recently. This short trade on the other hand, aligns with the current whip-saw like structure of the price action.