"If the yen (usdjpy) were to fall below 100, where would you expect to find support and at what level would one feel most confident to buy in (I.e. long dollar, short yen)?"

David Fuller's view USD/JPY (daily, weekly & monthly historic) has seen its 4th approximately equal sized reaction since February. Therefore, if this BoJ influenced consistency is to be maintained, it should rally quite soon. I would need to be a fly on the wall in the BoJ's policy meeting room to know if they understand or care about chart action, but investors and traders will certainly be watching and asking similar questions.

Meanwhile, a rally back above Y100 which also offsets Friday's decline is the minimum required to suggest that demand is regaining the upper hand. Tactically, one could anticipate this with perhaps a partial long position.

However, I would not be too aggressive because the Nikkei 225 Index (daily, weekly, monthly historic) commenced a medium-term correction with its big downside key day reversal on 23rd May, which also produced a weekly key. For perspective, see the monthly chart above for the Kyoko Koizumi rally commencing in 2003, which did not peak until 2007. It was the biggest rally since Japan's secular bear trend commenced in 1989. There were three significant reactions along the way, of which the 2006 setback was the sharpest.

I maintain that the Shinzo Abe rally will be bigger, for the following reasons: 1) Mr Abe and the BoJ quietly express a preference for a weaker yen, because it has only seen a modest rally compared to its long slide shown above; 2) They will also continue with their reflationary policies; 3) Japan's stock market is historically cheap but it needs a significant economic recovery to revive Japan's vitality; 4) the Nikkei's 2008-2009 lows are only slightly beneath the 2003 low, establishing the 7000 region as a major floor; 5) The USA wants a stronger Japan for reasons of global economic stability; 6) Japan is unlikely to face a 2007-2008 credit crisis anytime soon, although it will eventually experience the end of QE.