Obtaining a spouse visa

What specific supporting docuements are needed to obtain a spouse visa. My wife is a Japanese National.
Also, is there a minimum period of residence required in Japan before you could leave Japan to visit relatives etc.?

What specific supporting docuements are needed to obtain a spouse visa. My wife is a Japanese National.

I strongly recommend to ask the Japanese consulate or embassy in your country for the documents needed for your specific case.

Also, is there a minimum period of residence required in Japan before you could leave Japan to visit relatives etc.?

No. You could theoretically leave right after arrival, but don't forget to get a re-entry permit (inside Japan) to keep your status on re-entry.

You can also begin at the local City Hall in the city in Japan in which you reside or intend to reside.

The paperwork, requirements, and process vary quite a lot depending on whether you intend to enter Japan on a spouse visa or enter on a different visa and changing later to a spouse visa. I'm assuming its the first case, in which the city hall will not be able to advise you properly, and I strongly second getting in contact with your local embassy or consulate ASAP as the visa approval process can take months.