this might not be an answer but since it worked for me and I know two other people like this let me tell you.
so if you go to japan and make japanese friends you'll be thinking in japanese in no time.
specially if you put your self in a situation where you are forced to not speak english it will be like second nature.
it reminds me when I first came to america.
I was forced to speak english and made a few american friends.
then in just a few weeks I had a dream and I was dreaming in english. lol
I remember speaking and thinking in english in my dremas because my american friend was in it.
so I guess you should make a japanese friend who don't speak english at all.
and hopefully he/she will be in your dreams one day
