Airfare is pretty expensive from the US. Obviously there are budget options such as Zipair from the west coast but I looked into it and by the time you add in baggage and choosing a seat, plus a repositioning flight, it's not such a great deal unless you already live near LAX/SFO/SJC. Flights from the rest of the US are in the realm of $1000USD each way, for direct flights. There are some cheaper times of year but the trend definitely seems higher than ever. Definitely more than I have ever paid in airfare, anywhere! Plus with losing about 3 days to travel with the flight length and time difference, Japan isn't a great destination from the US unless you can take off at least a week and a half.
So, even if being in Japan itself is cheap, the barrier to entry is pretty high from the US, unless you are near LA and can take advantage of some of the cheaper (and quicker) flights that pop up. I have a lot of friends that would love to go to Japan but the flights are just too much and it's also tough to take so much time off work. Everyone I know is going to Europe instead since flight deals are much more common, and obviously it's a bit shorter of a flight. They all see the Fantasy Springs stuff are like wow!!! But for us, going to WDW (especially with an AP) is just a far cheaper option. It's funny to say WDW and cheap in the same sentence, lol!