YYC-YYZ-NRT will probably put you over MPM. Even on a reward ticket, your total milage from origin to turnaround may not exceed 125% of the actual distance.
YYC-NRT is 4973 miles. MPM on the route is 6216.
YYC-YYZ is 1675, and YYZ-NRT is 6439, which is well over the milage limit.