Work remote for US company while on student visa in Japan

Hi all. I’m going to a language school after a few weeks. My company is ok with working remote and as a contractor. I’ve read a few posts here saying that people can do 個人事業 for this situation. But still confused with some questions

1. Is student visa allowed to apply for 個人事業?
2. Does my company have to have a site in Japan?
3. Are there any documents that my company need to provide?

Thanks in advance!