The surge in EWJ reflects strong rallies in both the Nikkei and the yen. This does not happen often and sometimes they move in opposite directions.
The spectacular rally in Japan was long overdue and still has quite a way to go IMHO. Bot on a more sober note, I have long felt that a strong Japan rally would mark the final phase of the global bull market in stocks and bonds since it means the end of ultra cheap money over there.