Visa question

Hi,
Right now I am an ALT but I've been in Japan for 3 years and have been studying Japanese for about 5 years. I would like to try working in something like a cafe or restaurant to take a break from English teaching.
Language skills aside,

Can I legally do this?

Can I just walk up to a cafe or restaurant with a help wanted sign, ask for an interview and if I get the job, go down to immigration and change my visa status?

The thing is, there is no working visa status allowing you to work at a restaurant or a cafe. Even if there were, you still need supporting documentation from your new employer to change your status, plus proof that you are earning enough to live comfortably (the 1,000 yen or so an hour that restaurant jobs usually pay won't be enough).

If you continue teaching English, but want to work at a restaurant part time, Immigration may grant you permission to do work that isn't covered by your visa status, but they may also refuse.

Yes I've been thinking about it and I just want to try working part time for now in something like a cafe. I just want to try it and of course to pick up some extra cash.