Non-native English teacher from Finland

Hello everybody! I am New at the forum and I know that this question has been asked here a number of times, but I would like to know my chances of English teaching in Japan. I am planning on moving to Japan with my Japanese wife and look for teaching jobs with spousal visa. What I have learned, is that the visa is often the problem in job Hunting. Also being non-native have issues. I consider tough myself as fluent speaker. I am now 30 years old and have a college degree in business. I have also been working earlier in kindergarten and have experience teaching programming in elementary schools.

So, long story short, what are my chances of teaching in Japan?

You are correct that the biggest hurdle is visa related, so in that respect you should be fine. With a spouse visa, the only issue will be getting a job offer, which should be fairly straightforward presuming you are fluent enough to satisfy the interviewer and without too heavy an accent.