With the us dollar so low against nearly all currencies why does it continue to do well against the Yen?

I don't understand the strength of the dollar against the yen. How come it does so well against the yen? Is it the fact they have low interest rates in japan? I am making money in the stock market, but am finding that I am making more dollars that are worth less v other currencies. Any opinions on just buying yen and betting they'll appreciate against the dollar or the yen's weakeness some sort of statistical or mathematical imbalance/anamoly. I doubt that...just wondering what the math whizzes think about it.