Katolec Corp. (www.katolec.com/art.html) is the only shipping company in Japan that is a member ICEFAT. If you have not contacted them yet, they might be able to help you.

I don't have any personal experience shipping to Japan or with Katolec Corp. I'm located in China and the import/export rules/regs here are a totally different game. Let us know what you find out.

Good luck.