The cost to ship each set is approximately $60 each, so I wouldn't be able to ship them to Japan for free. If you would like for me to ship directly to Japan then I would have to add this cost.
I sell many items to Japanese customers but they usually have a forwarder in the United States that I can ship to and their forwarder will handle all the details to ship to Japan including customs documents and fees.
I hope that answers your question. If you have any other questions then please let me know.
私共では多数の日本のお客様とのやり取りをさせて頂いておりますが、皆様、米国内のフォワーダーをご利用されており、私共からそのフォワーダーへ郵送し、その後はフォワーダーにて税関書類や料金などの全ての処理を担当して頂けるようです。
以上でよろしかったでしょうか。その他何かご質問等ございましたら何なりとお申し付けください。