What the examiner is actually looking for

Three things, in this order.

Is the marriage genuine? Not whether it is happy, but whether it was entered into to live as a married couple rather than to obtain a status. This is judged from the questionnaire, the consistency of the account across documents, the photographs, and the communication records. Specific, checkable detail persuades; generalities do not.

Can the household support itself? There is no published minimum income. In practice offices look harder below roughly 2 million yen a year, and look at savings, housing costs and whether anyone else depends on the same income. A modest income supported by clear evidence is better than a larger one that the tax certificate does not confirm.

Is there anything in the record that contradicts the account? Overstays, unpaid residence tax, undisclosed previous applications, or a criminal penalty that the form says was not there. Almost all serious problems in spouse cases are consistency problems, not eligibility problems.