As a resident in Japan, I was thinking about putting online a small website to sell some items (not candies) to Europe and US residents, however a friend warns

As a resident in Japan, I was thinking about putting online a small website to sell some items (not candies) to Europe and US residents, however a friend warns me it would not be as easy as I think. Could you give me some info about how you started? Especially about the legal and taxes aspect. More precisely, can I start without a company? If a company is needed, 個人事業主 or 合同会社? Is this even compatible with student visa? The tech aspect in not a problem, but starting the business side seems super tricky.