Yeah, definitely strange that he wouldn't try to make contact through other means if it was just a lost/broken phone. Though not knowing him, maybe there's another benign explanation (skiing somewhere where there's no real service, partied too hard or got sick and is out of commission for a day, etc.?).
You could try contacting Emergency Assistance in Canada; they might not be any help. But it could be worth a try, particularly if the consulate in Japan is closed on Monday:
https://travel.gc.ca/assistance/emergency-assistance