My trip will be from Vietnam to Canada. I will have a 4 hr layover in Tokyo.
I am a Bangladeshi passport holder and permanent resident of Canada.
Will I need a transit visa for Tokyo airport?
If you have a Canadian passport then you will be able to get a visa on arrival for 90 days.
Otherwise you might need to apply for a visa before travel.
Regarding a transit visa you should also contact your airline; many airlines assist/sponsor a transit visa based on certain conditions