Keep in mind that the exchange rate of US vs Yen is 1:117.xx, if it drops to 116.xx, another drops will comes.
Although there is a meeting of Japan with other nations to talk about the Yen exchange ratio in mid. Aug., I don't think Japan will increase the interest rate because it will cause impact to Japan export => Japanese companies will object, and also, the Japan Prime minister will not against them especially now.
So, imagine when Japan annouces the interest rate keeps on change, what will happens to the exhange ratio and thus the US stock (carry trade) ?
The above doesn't include the second mortgage in US ....