Second generation Japanese
If the father or mother is Japanese, the application is accepted, even if he/she has not been resident in Japan for more than five years.
Article 6 Japanese Nationality Law
The Minister of Justice may permit naturalization for a foreign national currently having a domicile in Japan who falls under one of the following items even if that person has not met the conditions listed in the preceding Article, paragraph (1), item (i):
(i) A child (excluding an adopted child) of a Japanese citizen, the former continuously having a domicile or residence in Japan for three years or more;
(If you are second generation Japanese)
(ii) A person born in Japan, and continuously having a domicile or residence in Japan for three years or more or whose father or mother (excluding an adoptive parent) was born in Japan;
(iii) A person having a residence in Japan continuously for ten years or more.