After the international student graduates and changes to a Working Visa for employment, is it possible to work part-time until he actually starts working at the new employer?

International students in Japan are allowed to work outside of their status of residence up to 28 hours a week if permission is obtained.
If international students continue to work in Japan after graduation, they will have to change to a Working Visa.
II think that many students who had a part-time job while studying abroad want to continue working part-time until they actually starts working even after changing to a work visa.
However, simply obtaining a Working Visa does not allow a person to work part-time.
Therefore, if you want to continue working part-time until you actually starts working , you will need to obtain a new permission to engage in activity other than that permitted under the status of residence previously granted.