changing visa

i know this might sound absurb but is it possible to change visa,
from working visa engineering category to labor skill visa (i dont know the exact name how to call that, but a visa that can let me work in a restaurant, factory or any arubaito)
reason: it is hard to find a job within my category. ofcourse i am studying nihongo but i cannot be n1 overnight. i cannot afford also to be a full time student.

you might suggest english teaching as a job but i would rather work in restaurants than teach english.

"Skilled labor" visa doesn't just allow you to do work in restaurants, factory or "arubaito." This category comes with several defined types of jobs, such as chefs and architects skilled in specific architectural styles, etc.

What you seem to want to do is not possible.

so what type of visa should i have?

There is no status of residence that will allow you to engage primarily in the kind of jobs you mention.

Sounds like an unskilled visa category - they (Japanese immigration) don't need to offer one.

They don't offer one. To say they don't "need" to makes no sense, they are just doing their job, which is to implement the law.