You need to inform your gaining command or the agency you will be working for in Iwakuni as soon as possible. Special coordination for receiving you aboard the base will need to occur.
If possible, you are strongly encouraged to book a seat aboard the Patriot Express to avoid the difficult process that follows. Upon arrival into Japan, if not coming aboard the Patriot Express, you and your family can expect to be stopped at your point of entry by the Japanese government, tested for COVID-19 and be required to take a shuttle to one of the below locations for restriction of movement (ROM). If your flight is arriving into the Tokyo area, you must conduct ROM in the Tokyo area, no exceptions, therefore do not make a connecting flight reservation. The following hotels are the only approved locations for you to conduct ROM in the Tokyo area:
Upon completion of ROM at that location, you will be authorized to proceed to MCAS Iwakuni. If you use commercial means for your final leg of PCS to Iwakuni (train, bus, airline) or the Patriot Express, you will need to conduct ROM upon arrival in Iwakuni, again. If you take a MilAir flight (other than Patriot Express) or you are picked up via POV or GOV from your ROM location, you will not need to undergo ROM again upon arrival in Iwakuni.
If your flight is arriving into Kansei (Osaka), Fukuoka, or Hiroshima (if flying in from Okinawa), you must be picked up at the airport and driven back to Iwakuni, without stopping. Upon arrival to MCAS, you must undergo ROM on base and anyone who was in the vehicle with you must also undergo ROM.
This process is difficult, which is why the Patriot Express option is the much more preferred course of action. Engage your sponsor and gaining command early and often throughout this process.