My thoughts. Even though I don't know the complete story, if it was me, I would somehow try to bring him home (USA) he obviously loves you all, and you all obviously love him much. You may regret your decision later if you dont bring him home with you, and something happens to him in japan. I just know, if it was me, I could not ever forgive myself....but thats just me. You must think about it (I'm sure you have) and do what is best for him and your family situation. best wishes to you all.