What is the requirement for applying for Permanent Resident, “In principle, you must continue to stay in Japan for 10 years or more.”

One of the requirements for permission for Permanent Resident is that "in principle, you must continue to stay in Japan for 10 years or more."
“Continue” means to continue to stay in Japan without losing your status of residence.
Therefore, if you leave Japan without obtaining a re-entry permit, your status of residence will expire, and your period of stay in Japan before departure will not be considered when applying for permanent residence.
Also, even if you have left Japan with a re-entry permit, if you have lived overseas for more than half of your period of stay, you may not be considered to have stayed in Japan for more than 10 years.