Tax Filing- Japan PR living outside of Japan

Hi
I am Japan PR holder, I left Japan end of June 2015, I had my salary until then in Japan thereafter there is no income in Japan
Now in Dec I got Gensen choshu-hyou from my employer, there are 2 forms one for which i was consider as a tax resident and other for which I was not considered as tax resident (this was basically some bonus income after I had left Japan so my employer considered me as non tax resident and deducted tax at flat 20%)
My questions is
1) How do I go about filing returns when I am not physically in Japan - note I have never filed return during my stay in Japan and just withholding tax statement was enough
2) during filing can I expect that non resident deduction at 20% to come down to lower bracket - by considering me as resident?

If you guys have suggestions on any account who can help- please suggest me the same

You might want to contact your former employer (or National Tax Agency) to ask if you need to do the tax filing yourself. You have not taken up any other employment in Japan during 2015 since you left that employer, correct?

Since you did receive salary and bonus in Japan during 2015 and then left the company, your employer has not done the year-end adjustments (as they would have during the years you used to work full-year there). In some cases you "might" end up paying too much income tax (as the withholding tax is based on estimation).

But I have no idea about the exact amount, and the procedure when you are outside Japan (you have not appointed any tax attorney before you left Japan I assume). Or maybe your former employer could take care of that...