Moving to Japan as a personal banker for a credit union

So my S.O and I are getting married (not sure exactly when) and she is a Japanese citizen, we have been thinking about moving to Japan (her moving back and me going for the first time) in a about 5 years which should give us enough time to save up and me to get a degree in my industry (since I am not college educated and I heard that helps a lot) and learn Japanese fluently by taking classes

My question is, can I start the visa application process in advance?

And what does the banking/finance industry look like compared to the US from someone who has experience both?

Are there finance jobs that are more suited to foreigners like myself in Japan?

What are some things I NEED to know before even thinking about moving?

I will start browsing the sub for more info as I’m sure there is a lot of answers to my questions but thank you in advanced!

Edit: I’m going for my bachelors for science of finance and since I work full time and my work will pay for it it will be an online college, would that be a good way to get a banking/finance job? Any particular companies to seek out for employment?

Edit 2: apologies I will review the rules before I ask another question