[Lazarus]

I couldn't imagine travelling alone in Japan at 16, you are pretty courageous. One issue is that you may be too young to get a full credit account with an overdraft. I can't imagine running out of money alone in Japan is much fun..

Without a travelling companion I would, personally, certainly get quite lonely, especially if my Japanese wasn't of a high enough standard to meet people and make friends.
But yeah, having the balls to go to Japan alone at 16 is quite commendable! You would certainly have an unforgettable experience.