10-year residence in Japan is required. If you are spouse of Japanese nationals, the duration shorten into 5-years residence.
Once foreign resident is authorized to stay in Japan with “Permanent Resident”, it provides much more advantageous treatments than other statuses of residence. It does not limit the status holder’s activities or period of stay.
For this reason, the immigration control authority needs to examine permanent resident applicants much more closely than other applicants for merely changing their status of residence.
Here are more details about requirement :
Guidelines for Permission for Permanent Residence
(March 31, 2006, Immigration Bureau of Japan, The Ministry of Justice)
There are three types of naturalization; from easiest to hardest
- Kani Kika (simplified naturalization)
- Futsu Kika (regular naturalization)
- Dai-kika (extraordinary naturalization)
Kani Kika is for people who are married to a Japanese citizen.
If you are married for more than one year, the five year residency requirement under Futu Kika (regular naturalization), shortens to THREE years.
If you’re married for more than three years, then the residency requirement shortens to ONE year.
Futsu Kika is for people who are single or married to a non-Japanese national.