Quick FYI for those traveling with a stop-over in Narita: If you have ever transited through that airport, you know you have to go through security again, regardless of origin/destination of your flight. I've been flying internationally for 30 years now, and this is the first time I've experienced this - Narita will NOT let you carry on items bought duty free from another airport, WTF!? I purchased liquor in US airport Duty Free, sealed in bag and headed to me at the gate, so no possibility of placing in checked luggage. Arrived in Narita, went through their security, agent seized the bag with bottle of Vodka and Kahlua, and confiscated it. I raised a bit of a fuss, saying it was sealed, never opened, etc. Wouldn't budge, so I asked to check it in, he said sure, go back will take about THREE HOURS! my connecting flight to Manila was in an hour, so not possible. I was visibly pissed, so they called additional security, standing by. At that point, nothing could be done, just let it go and got on my flight to Manila, MINUS 2 liters of good liquor.
Few days later, someone mentioned that this could be economic, i.e, shop at Narita Duty Free, not at your source airport. Not into conspiracy theories or such, but on the way home, the Duty Free at Narita had a poor selection, with prices much higher than the US.