patio11's reply is correct as far as I know, but I'll pitch in a little more. When I was researching setting up my business in Japan, I was told I would need to hire a resident to be a business manager in the case that I wanted to sponsor my visa through the company. So this may be what you are running into. In my case I was getting a spousal visa, and incorporating after immigrating, so I could be the resident if I wanted.
But the problem is that you can't change your study visa to a working visa (BTW, this is not legal advice! Make sure to check what I'm saying with a lawyer). So you will lose residency when you change visas.
Potentially the easier way to go (assuming you are doing some high tech thing and you are getting an equivalent to an "engineering" degree -- CS should be fine) is to get a job and have the company sponsor your visa. At that point you can start your your company no problem and hire yourself. This is one way to avoid having to sponsor your own visa (which will have capitalisation requirements).
I was in a similar situation before I got married. I was teaching English and I wanted to set up an IT consulting company. My visa was as an instructor and there was no way to switch it to an engineering or business person's visa. So I would have had to sponsor my own visa. As it turned out, I got married, moved to the UK for a few years and then set up my company when I returned.
Edit: Even easier approach (though time consuming) is to get a job and stay long enough to get permanent residency. Then you have no issues at all. Minimum time frame is 5 years IIRC. Normally being married helps a lot, but I suspect if you have gone to school in Japan it will help equivalently.
> But the problem is that you can't change your study visa to a working visa (BTW, this is not legal advice! Make sure to check what I'm saying with a lawyer).
Sure you can, I have done it and I know tons of people who have too. Usually no lawyer required; assuming you have a degree (or is going to graduate soon) and you have a job offer, just apply at Immigration.
Note that technically you don't "change visas" -- visa is something that's required in order to enter the country -- you change "status of residence". Usually people use the terms interchangeably, though.
But this is exactly the problem. In the scenario you describe, the company is sponsoring you. In the situation that the OP is describing, they want to start a new company. But they can't do that without having an employee who is a resident. And they can't work for the company without having the company sponsor them. It's a catch 22. Like I said, I would check with a lawyer, but I'm 99% sure it can't be done. If you are already have a working status in the correct field, then it is no problem. But you can't change from one to the other without sponsorship. That was exactly the problem I faced trying to change my status from instructor to engineer and also trying to work for my own company without sponsoring myself.
Edit: I should also point out that hiring a part time Japanese resident fixes all the problems. But that was what the question was all about.
Ah, got it. If you're a student you can apply for a permit that allows you to work part-time. But I don't know if a part-timer would count as an employee of the new company.
