It is a system that allows foreigners to continue living in Japan as foreigners, and it is different from the system of naturalization that acquires Japanese nationality and becomes Japanese as a law.

Also, the renewal procedure is unnecessary.

Although it is a difference between permanent residence and naturalization, nationality does not change in permanent residence. It's not become two nationality if you change to be naturalization.But naturalization of that person loses the original nationality,and it'll become Japanese nationality to Japanese people.