Troubleshooting

TurboTax will only show you the Quebec forms if you choose Quebec as your province. So you would have to choose Non-Resident to create your Federal return. Then create a copy and change the province to Quebec so that you can fill out the forms for Revenu Quebec.

You would only put in an amount for Other Canadian-source income if you haven't already entered it somewhere else.

You would enter your Japanese salary as Net employment income on the Statement of World Income  page.

Yes, you can print & mail only your Quebec return. You will need to as you won't be able to transmit it digitally. When you get to the end of your return, choose Print & Mail instead of NETFILE. You'll separate options to download the CRA copy & the Quebec copy, so you can choose just the Quebec one if needed. This Revenu Quebec page tells you where you can mail your return: Filing Your Income Tax Return by Mail