Here’s the law: your SIN number with a 9 means your a landed immigrant. It doesnt mean you dont pay tax.
If you normally live in Canada, or are here for more than 183 days
you probably have to pay tax on all your income for that time from everywhere, not just Canada income. Same as Japanese rules.
You can make about 8,000 a year and not pay tax, maybe a bit more if you are a student. In Japan your company does your tax return, here YOU do it.
If you are going to be here for more than a year, file a tax return even if you made no money, becasue you can get GST refund cheques, and other cheques from provinces.