Hi little-fish, welcome to FlyerTalk!

Why don't you try using the ITA fare search engine to look for your flight? You can't buy tickets from them but it helps you to locate the best deal:

http://matrix.itasoftware.com/cvg/dispatch/login

Currently ITA is showing $1273 CAD as the best price throughout November for a 1-week a stay, departing and returning Monday-Thursday. That's on United (UA), though they are a Star Alliance (*A) partner with Air Canada (AC). $1207 on AC may be one of the better prices.

There are a number of fare experts on the Japan Forum who can give you greater detail, but ITA is always a good place to start.