This is a notice from the Immigration Services Agency of Japan.

Due to the effects of the new coronavirus infection, those who have difficulty returning to their home country and wish to work will be allowed to work within 28 hours a week (part-time job).

For details, please check the leaflet below.

Handling of foreign nationals who have difficulty returning to their home country
or other country

For foreign nationals who are unable to return to their home country due
to the COVID-19 pandemic and wish to work (part-time) to maintain their
livelihood in Japan

Detailed contents are also written on the Ministry of Justice website. There is also a multilingual version.

http://www.moj.go.jp/isa/nyuukokukanri01_00155.html