Depends on which airline that you will be using for getting back to Canada. If you are using Air Canada for most of the time, of course you should join any of the Star Alliance members as you will be eligible to redeem ticket from any of them. A ticket to Tokyo will cost you as low as 20,000 miles if you are United Mileage Plus members.
If you are taking CX for most of the time, join Asiamiles then. The lowest redemption class is 15,000 miles to Taipei, but they need 35,000 miles to Tokyo.
May I know which star alliance programme you are in? I am members for both mileage plus and krisflyer but I only need 25,000 miles to either Bangkok or Tokyo (return ticket already). For ANA, if you choose the early departure flight, they require more mileage from you. But if you are taking the afternoon one, seems that they are charging 25,000 miles also.
I am not too sure if it is the Royal Orchids Plus that require so many mileage to redeem a ticket. For Krisflyer, they require only 25,000 miles, and you can choose between UA or ANA to fly. For UA mileage plus, they just require 20,000 miles to fly to Tokyo on their own carrier. Hence I think Thai Airways should only charge you 25,000 miles per return ticket to Tokyo (max.) even if you want to fly on ANA.
If u have JAL Mileage bank a/c and your miles have been credited to this account when you travel to Canada, and your account have accumulated up to 20,000 miles, you may redeem one return ticket to Japan, on economy class.