but what about my 10 days off. If I am a passenger on say Air Canada inbound from Vancouver. I arrive in Tokyo as a regular pax. Surely if my citizenship requires a visa for Japan ( I am not Canadian) then I would need one in this case.
No, this is how it works:
When you come in as a passenger on the inbound flight to start your roster, the company will arrange a shore pass with a permit from Immigration and you are handled by a company representative that waits for you at the arrival gate and takes you through immigration as a dead heading crew. When you do your last flight of your roster, there is a company rep. that greets the flight and gives you the shore pass with another permit that transfers you from operating crew member to passenger and it is handled by immigration again as a dead heading crew, there will be no need for a tourist visa on your commute.