So I decided to leave and move to the Bay Area. I spent a decade there building up work experience and saving money, until an opportunity came to move back to Japan. It’s worked out well, I am financially independent with a job that I mostly enjoy, and having moved away for so long and then returned I am really confident now that this is where I want to be living.
I would suggest that you consider a similar path if possible. I personally found it so much easier to develop my career in my home country, surrounded by all the opportunities that SV offers programmers.
I can’t really comment on how best to go about filing all the necessary paperwork for your business, but if possible I would recommend trying to do things according to the letter of the law. As you’ve no doubt already learned Japan can be fairly strict with regards to process and paperwork, and I would hate for some misstep now to come back to bite you later e.g. when applying for a visa. But this is of course all secondary to taking care of yourself right now.
And that brings me to the suicide part. I’ve also been there at one point in my life, suicidal and so depressed I could hardly get out of bed for months at a time. I had this horrific tunnel vision, and the things that were stressing me out at the time made me feel hopeless even though there were plenty of opportunities to be happy staring me in the face every day. But gradually I got better, learned to cope with my problems, and I honestly think those hard times helped me to better understand myself, my limitations, and shaped me into a person who is genuinely grateful for all of the amazing things that have happened in my life since I failed at suicide.
It sounds like you’ve had a pretty serious setback - but it’s only temporary. I hope you are able to get back on your feet again soon!