Changing address issues

Question: is there any way to obtain 転出証明 without going to the city hall of the city I moved out of?

Address is registered in Nara, 2 months ago I moved out of the house, stayed with a friend in Osaka for 6 weeks, then 2 weeks ago moved to Okinawa.

I went to the 市役所 here to register my address and they said I can’t without the 転出証明. I was unaware I needed to notify the Nara city hall when I moved out (at the time I was planning to leave Japan but found work in Okinawa).

I have someone in Nara who could go to the 役所 for me if that helps.
My boss suggested I could give them power of attorney (委任状) by writing a letter, and have them go to the Nara city hall on my behalf but someone else said I would need a hanko which I don’t have.

Have a day off tomorrow, planning to try and make some calls to find out what’s possible, go to the city hall again, also to the immigration office to apply for visa renewal as well as ask for their advice.

Any insights appreciated.