What restrictions do I have with regards to working in Japan?

Question

I have a 5-year Japanese working visa (engineer) and I'm currently working for a Japanese company. I'd like to know what restrictions there are on what work I can do here, but I can't find any sources on what my visa actually allows me to do (Googling anything to do with 'Japan' and 'working visa' just brings up hundreds of results about how to get a visa).

I'm aware that I am restricted to working within my field (engineering) but would it be legal to take remote work from a foreign company? Or what about starting my own business? I assume either of the above would make it difficult to get a renewal once the 5 years on my visa are up, but how about until then?

Could someone perhaps point me to a source where I can find this information?

Answer 1

I'm aware that I am restricted to working within my field (engineering)

Not exactly. "Engineer" status is more general than just engineering and covers all jobs requiring scientific or technical skills other than those specifically covered by some other status such as "Researcher". The legal definition is

Activities to engage in services which require specialized skills or knowledge pertinent to the field of physical science, engineering or other natural science fields [...] (except for the activities listed in the right-hand column of the "Professor", "Artist" and "Journalist" sections in Table (1), and the activities listed in the right-hand column of the "Business Manager" to "Instructor" sections, "Intra-company Transferee" and "Entertainer" sections in this Table) based on a contract entered into with a public or private organization in Japan.

The jobs you can do are precisely those that, in immigration's judgement, fit this definition.

would it be legal to take remote work from a foreign company?

The law says nothing about remote work; the general consensus is that immigration does not care about it, and so for immigration purposes, remote work from outside Japan is the same as no work at all. So on the one had, yes, it is legal (no matter the type of work) since it does not constitute working outside your status. But on the other hand, if you do only remote work, as far as immigration is concerned you are unemployed, and so your status may be revoked and even if it is not revoked you will certainly not be granted an extension.

Or what about start my own business?

Management of a business belongs to "Business Manager" status, and is explicitly excluded from "Engineer" as defined above, so no, you can't start your own business.

Answer 2

Engineer is usually under the visa category "Engineer / Specialist in Humanities / International Services" which is defined as:

Activities to engage in services, which require skills or knowledge pertinent to physical science, engineering or other natural science fields, or to engage in services, which require knowledge pertinent to jurisprudence, economics, sociology or other human science fields, or to engage in services which require specific ways of thought or sensitivity based on experience with foreign culture, based on a contract with a public or private organization in Japan [...]

This means basically any job where you are using your technical knowledge, language knowledge, or international knowledge should be OK. Starting your own business is a grey area. You could probably do a small (not limited liability) company on the side, and even then it would be a good idea to ask for permission from the immigration office first, but this visa is "based on a contract with a public or private organization in Japan", so you should still keep your sponsored job.

Here is the List of statuses of residence of Japan, if you wanted to change your status of residence in the future.