When a PR holder applies for landing permission onto Japan, he or she needs to show their resident card and re-entry permission at a port of entry. The validation period of the card is seven years and the period of re-entry permission is 5 years upon application or 1 year without application. You have to return to Japan within those periods, otherwise, you will lose your PR status. There is no regulation to stay in the country for a certain duration to keep PR status.
