I'll add to this post by saying that I live in Japan so, if you can't find the flavour you want, I am happy to buy it and send it to anyone. Obviously, I'd expect the person to cover the cost. I imagine it would be same/cheaper than buying on Amazon though.
Amazon Japan Kit Kat search: http://www.amazon.co.jp/s/ref=nb_sb_noss_1?__mk_ja_JP=%E3%82...