Not sure how much of value my experience booking our spring trip will be to the OP but...

We flew YVR to NRT on the way there and ITM to YVR (with a connection in NRT) on the way back on JAL. Price-wise, it was pretty comparable to Air Canada but we wanted to try JAL. We booked during an initial seat sale but there was a subsequent seat sale about a month later for $100CDN cheaper (with a corresponding seat sale at AC).

We booked through IACE. They have a Canadian website (which they've now set up English pages). We booked at the office though (they also have an office in TO). Their site seems to be showing $778 from YYZ to NRT before taxes and fees.