Do airline tickets to Japan get cheaper as the flight gets closer?

I am leaving for Japan on August 26th for my study abroad outside of Osaka, but I looked at STA Travel today and the cheapest ticket was $1450. I'm going in May and tickets were only around $900 on Northwest, but NWA wasn't even a choice on Expedia or STA (yet). Plus, there were only options for two layovers. I'm flying from Raleigh (North Carolina) and I would prefer not to lay over in Charlotte and San Francisco, so if anyone has any information that would be great. In may we are only having one layover in Detroit and that would be much preferred to multiple ones!