It might be true that you could get visa here easier than china, but J-1 is very different from B-1, it requires that the applicant must have the similar position or do the similar work in his or her home country. If you have been here for a while, how can you convince the visa officer that you still have a position in China or very strong tie with China?
P.S. The visa officer in Osaka may be very nice, much better than the guy in Tokyo, then you can have a try.
Good luck!