Path to self registered

I know that question has been asked before but since my situation is different than others I figured I could ask as well.

I have been living in Japan for 7 years now and have secured 2 new contracts with my boss. I get paid ⅔ of what used to be my salary as an English teacher and the last third as an independent to make his website among other IT things.

The point is I need to register as self-employed to declare this amount to the government.
My plan is to leave English teaching progressively to become 100% self employed, I will do free lance work not just for my boss but also other customers online.

I heard if you can prove an income of 250000yen per month you don't need to be sponsored by a company anymore so I could then work as an independent forever in Japan.

I will get my first paycheck as an independent on the 10th of June. And I am trying to sort out all I need to do.

This IT work will make me 120000yen per month for now but hopefully more once I find customers online.

Thank you for your help

So I am assuming that you have been (so far) employed full-time by one employer under Engineer / Specialist in Humanities / International Services resident status, and want to go independent.

For you to be able to renew the current resident status while becoming a freelancer, yes, youfd have to be able to show that you will/do have continuing contracts with multiple clients, revenues from which would add up to a certain amount per month. As far as I know, what the immigration authorities will look for are that the nature of the work you do is in line with the requirements for the engineer/specialist inc status, that the remuneration is in line or higher than the locals would get, and that there is continuity and stability in the contracts you have/will have (they will want to check the contracts for the term, remuneration, location, etc.).

In light of that, it might not be accepted if the work is completely remote/work-from home, because then you would not need to be in Japan, or if the nature of contracts are short-term/spot jobs. I have heard that there will be gone main employerh who would be paying you the largest amount among your clients, and they need to present the case that you are needed in Japan.

Also once you become a freelancer, youfd need to do your own tax filing, enroll in the national health insurance/pension systems (not the ones provided by the full-time employer so far), so if you need one, you might want to look for a tax accountant.

You might want to consider retaining an administrative scrivener to get some suggestions. Best wishes.