Dollar rises against the yen?

The last few days has seen the U.S dollar rise against some of the major currencies. but with not much buoyant fiscal data to support the sudden strengthening of the Dollar one can only wonder whether it is the Japanese central bank that is hiking up the value of the dollar. If this is true, then why not the other currencies? Also, since the Euro has become a favorable reserve currency for most currencies, what is Japan's position on that....