Travelling from Tokyo to Okinawa

Hello! This might seem a silly question, I�fm on a WHV in Japan currently and living in Kawasaki. Am I able to travel to Okinawa via air and back without having to apply for the re entry permit? Or is this something I will need due to travelling by plane?

Okinawa is part of Japan. So, because you don't leave Japan, you won't have to apply for a re-entry permit. Even if you were to leave Japan, these days you do not need to apply for a re-entry permit anymore.

The only thing you need to fly domestically in Japan is a air ticket. A passport is not required. Your identity does not get checked. Flying in Japan is more like riding a train, except for the luggage check.