Unemployed workers who have previously been in continuous employment for at
least six months (twelve months for part-time workers) with the same employer
are entitled to receive the benefits of unemployment insurance.
The Employment Insurance system was created as a way to support workers should
they find themselves without a job, as well as to assist them financially as
they search for new employment.
All employers are obliged to enrol their employees in this system. This insurance
system is also available to foreign workers who are in possession of visas that
carry no restrictions on their professional activities in Japan, unless you
are employed outside of Japan or draw unemployment benefit from another country.
For more details you can consult Hello Work
or the local Public Employment Security Office.