I have a lot of Japanese friends, and my sister in law just moved from Japan to marry my brother in law.
Let me start out by saying, as an American, I LOVE Japan. I went twice last year, and I'm planning another trip this year -- it's somewhere my fiance and I plan on going every year [he's speaks Japanese pretty well]. It's beautiful, their culture is amazing, and the people are great... to foreigners. Visiting Japan is a lot different than living there though.
Did you happen to see the salarymen commuting home from work on the train at 1am? Almost falling asleep standing up? Do you know about their insane work culture? Do you know most people their work 6 days a week? [A friend of mine works in web there, and works 6 days a week 2 weeks of the month, and then works 7 days of the week the other 2 weeks of the month.. he gets 2 DAYS OFF a month]. Your boss wants you to go drinking after work? You MUST go.
Are you aware of the sexism in the workplace there? You're a 35 year old woman without children? I'm sorry, but they're going to be talking shit on you behind your back.
Are you aware of the subtle racism of the culture? I have a friend who works there as an English teacher -- he's a well to do looking guy from New Zealand. He gets stopped regularly and asked for his passport on his bike because they think he may have stolen it.
Have you seen the 'Japanese Only' restaurants there?
Japan is a wonderful place, but 1) You've only seen a small portion through rose colored glasses, and 2) I think you're being incredibly selfish to assume that this man would want to move back to a place where he probably feels like he escaped from. To have him back there you are dooming him to the life of long work hours and a harsh work culture just because 'I've only had the chance to stay for 2 weeks'.
Why don't you care about your soon-to-be husband's feelings enough to accept his answer on this topic? Stop being selfish, realize that he doesn't want to move there, and lay off this poor guy.
If I were him, I would take you pushing on this so much as a major red flag in the relationship.