Might be stuck in a bureaucratic loop, advice appreciated

So I am a dual citizen of Japan and USA, with both passports, and I recently moved into an Oakhouse apartment in Ota. I lived in the US my whole life until now, with many visits to japan. I went to fill out a move-in notice at the ward office, but a problem occurred; my Japanese passport was not stamped upon entry. The man at the office said he couldn't submit my form until I had a specific date and proof of entry into Japan, since I do not have a previous Japanese address.
He suggested I request a disclosure of immigration records, which I looked into. Part of the process of acquiring said records is providing an identification document with my current address, such as a mynumber card (which i don't have yet). If I understand correctly, I can't provide the needed documents without registering my address, which starts with a move-in notice, which I can't get without immigration records…
Am I cooked here? Any help or pointing in a right direction would be appreciated.

by nagesuteana