I am not an expert...but I don’t think you should write your Japanese address on the tax return. As far as I know, the return is for people who resident in Canada so you should’ve put your Canadian address to get it. I believe if your address is Japan, your eligiblity for tax would automatically drop, however if you come back to Canada and file for another return (e.g. next year), they do reassessment of your file and you would get the return even for previous year.
Hope some experts would clarify for you other than my comment...
EFILE needs an ACCESS CODE to file tax return. It’s usually given from previous return. So you have to file it more than one year with same SIN #- meaning it’s not really for people who are on working-hoilday visa and end up filing only one time for Canadian tax return.