If you ask the Embassy of Japan in Australia, the official answer would be to ggo the CoE path, from outside Japan.h To get the terminology precisely: either you apply for CoE and get a visa from outside Japan, or you come to Japan on Temporary Visitor, and apply for a gchange of resident status.h
The disadvantage of going the CoE – visa path is you donft know how long that is going to take, so that you canft really plan the flight & the relocation ahead of time.
On the other hand, once you do come to Japan already married, and apply for Change of Resident Status (from Temporary Visitor to Spouse of Japanese National), and once your application is accepted, you can stay with your spouse in Japan while you wait.
When it comes to the documents and guarantor/income issue, no matter what the financial situation is, your Japanese wife will be the one to sign the guarantee letter (form letter provided), in the sense of ensuring that she will make sure youfd abide by the laws of Japan, and in case you need to leave Japan she would be responsible for the travel expenses (as the gsponsorh for you, so to say, because she is the reason you are applying for the visa/resident status). In addition to that, you need to show that you (and/or your wife) will be able to ensure income enough to support yourselves going forward. This may come in the form of a financial guarantor (by a relative, in-law, for example), or you writing out a letter describing your business/skills that would enable you to make a living.
At least, writing up a letter describing our prospect was what we had to do when we changed from an employer-sponsored work resident status which my non-Japanese husband had in Japan to gspouseh status, when his contract didnft get renewed. He was out of work, and I was only doing very limited work back then.
This may be somewhat old, but maybe a remotely related thread, and I gave a longer answer there.
https://www.japan-guide.com/forum/quereadisplay.html?0+159380Best wishes.