This is the same with virtually every country in the world now.
But also there's probably nothing to stop you applying for non-resident tax status now (I don't know Canadian law, but most countries have similar arrangements and procedures in this mater).
To get non-tax resident status in most countries you just have to provide a bit of proof like:
- showing you don't have permanent ties to your old country - like a house (even if it's only been a rental and you've never lived in it), a tenancy agreement, a wife still there, a business, or a job contract etc.
- That you're out of the country for a certain amount of time (eg 325 days out of the last 12 months).
- It helps if you can show long term employment contracts from your new tax residency country (Japan), marriage certificates, tenancy agreements - that kind of stuff.
- Sometimes even if you don't fit all of these requirements you can still get it (the place of abode and the time out of country are normally not negotiable though).
And as long as you're not retarded and tell them you plan to return to Canada or something stupid like that, then you should get non-tax residency status.
And once you've got the status, the Canadian tax department will usually back date the status to when you first left the country permanently - so no auditing your Japanese income for Canadian taxes at a later date - or penalties for not filing your Canadian returns on time [late filing penalties] - or for not paying the tax owed, the amount that you did not even know you owed, when you should have [late payment penalties].
But it can also happen that you just never show up on the Tax man's radar (which has usually been the case as up to now as there is/was no automatic sharing of this information without a manual request by one of the tax agencies). Up to you if you want to take the risk or not.