Can I re-enter Japan?

(We are American citizens)

Anyways, my fiance is in the Military and is stationed in Japan. I have purchased a Ticket and depart December 1st and a return ticket back to the states March 1st. We will be getting married either right before my departure (thru proxy marriage) or with the Chaplin on base (in Japan). My question is, when we get married will I be able to talk with immigration into letting me stay till May 1st with the right documents and proof of marriage (as that is when he leaves Japan) or will I have to come back to the states, and if I do, am I allowed to go right back to Japan for another 90 days? I am young and have rarely ever traveled in my life, never out of the country.

I am also okay to hear any ideas from people that might make this go a little smoother, my situation is very specific and the internet does not help much. Thank you.

If your spouse-to-be is on base, and if you plan to get married on base, what you should look into USA dependent status under SOFA: Status of U.S. Forces Agreement, not Japanese immigration rules.

If you from America. You can just return with ease using the 90 day visitor permit each visit. No need to go through crazy paperwork for small visits.

I don�ft know about SOFA visa but as you don�ft plan to be here long the easiest is probably a short trip to Korea (or Taiwan or any other country) and return to Japan and you get a new 90 days.

We will be getting married either right before my departure (thru proxy marriage) or with the Chaplin on base (in Japan).
Getting married in Japan is pretty simple as a legal process, but you do need affidavit proving no impediment to get married (from Embassy), full birth certificate (and I can't remember the other docs - been a while - there is a form to fill out as well). Even if you use the base Chaplin, the religious side is less relevant as you still need to comply with the legal aspects, so sort out what documents you need in advance.
My question is, when we get married will I be able to talk with immigration into letting me stay till May 1st with the right documents and proof of marriage (as that is when he leaves Japan)
They will say "No" - pretty simple, the rules do not allow it. Only method, mentioned above is if you become dependent under the SoFA and that will require the commander to grant approval for you to be covered (as I understand the process - it is a topic that comes up occasionally in the forum. (Are you planning to live on base? )
or will I have to come back to the states, and if I do, am I allowed to go right back to Japan for another 90 days?
Yes, you could do that or somewhere a bit closer. You may be questioned about being in Japan for such extended periods of time with a short absence, but if you are a genuine temporary visitor you are allowed to leave and re-enter a short time later and get a fresh 90-day permit.