When I started this comapny, I didn't have a product - but I had the holding company (Contraption Company). My first product was Postcard, but now I spend most of my time building Booklet. As the shift in products has happened, my professional email address has been the same, the terms of service have been shared between services, and I have a unified blog + announcements email list. This also means I can launch lightweight experiments such as "FRCTNL", and even if it's not commercially successful - I benefit from compounding returns in the brand and mailing list.
The good news it that Japan seems to be in desperate desire of skilled foreigners, and announced plans this week for a digital nomad visa: https://www.japantimes.co.jp/news/2024/02/02/japan/society/d...
I've heard that the path from temporary visa to a more permanent one is somewhat straightforward for a self-employed person if you're able to show moderate revenue from Japanese clients.