The best and really only sensible way to ship wine is in a styrofoam container designed for that purpose. They come in 1, 2, 3, 6 and 12 bottle sizes and are widely available in the US. Cost is all of about $15 for the biggest size. Packing it in your luggage is just daft if you value the wine and the clothes. The wine in Japan at NRT is not worth buying. I ship tons of wine from the US to Japan as checked luggage and by using a proper box you will be perfectly fine with what you want to do. They one tip is have an extra roll of Packing tape handy as they may ask you to open the box.