[shintoist]

If you read the article the author does quote the US embassy in Japan strictly advising against this and that you risk arrest and deportation, that immigration officials do crack down on digital nomads, especially re-entering Japan to renew 90 day tourist visas to work.

A lot of countries have laws against working remotely without a visa, although apart from the US few actively enforce them.

[CharlieDigital]

Seems like the restriction would only make sense in the context of working for a Japanese company. Similar to US visas for visitors where the traveler cannot visit the US for work purposes with a US-based employer.

Otherwise, opening a work laptop and answering some work emails for your foreign employer would be risky.

[VincentEvans]

Precisely this - countries protecting their job markets against foreigners working illegally (not paying taxes, undercutting wages, etc).

This has nothing to do with you working for your own foreign employer while on vacation.