Make sure that your marriage in thailand is fully registered at the amphur.
It is not easy getting the non-o marriage visa here. Yes, can be done but there are a lot of requirements you must check out fully. It may be easier getting the non-o outside. You would have to check in japan.
You must have the 400,000 baht in the bank the required period.
For the first time application, I am not sure if the money has to come from outside thailand, like the retirement visa.
Dr Jack may help to advise.
First marriage visa non-o is 90 days.if you do not apply for the one year extension after the time reqiuired, then i presume you would have to do it again each time but i do not know and have no idea if/ what complications that would make.
Some suggestions are that you come in visa exempt for 60/30 days. If you are doing 3m returns, check how many times you may be able to do that even by air.
I only came back into thailand once in march after going out because of the expiry of my work permit.
visa exempt entry, and the immigration officer at airport warned me to come back in next time with a visa.