Once Japanese understand the technology and advantages of Bitcoin, they will accept it with no doubt.
Low fee if compared to international wire transfers, yes. Buying things, I don't think so.
Let's look at an example. In Tokyo at least I can use a PASMO/Suica card to buy a bowl of ramen. Say, 1000 yen (I know, pricey ramen). To get that money on the card I put a 1000 yen note in the machine and it loads my card. So there is 0.- fees involved for me as a user and can all be done in 5 minutes. Similarly, Edy can be charged for 0.- fees, if I'm not mistaken. And Edy I can use on Rakuten, Amazon (JP).
To get that amount in BTC, I would have to send money to the exchanges' bank (a bank fee there if it's not the same as mine), exchange it there (exchange fee applies) and, for convenience and safety, get the BTC to my wallet (another small fee there, potentially). No way that could all be done in 5 minutes. Additionally, since it does take longer, I'm exposed to the exchange risk. So what I thought I had put on my wallet to pay for the ramen, might not be enough by the time I finally make it to the shop.
So, no, I don't think the "low" fees will be the trigger for the Japanese to accept it to buy things.
I agree with you.
Adoption of Bitcoin in real-life scenarios is not as easy as online scenarios.
BitCash is widely used in online/mobile games in Japan which has a percentage fee for game developers.
If Japanese game developers find the advantage of Bitcoin and start adopt it, people will accept it just like they accept BitCash, which has 4 billion yen annual turnover.