Any person born in wedlock to at least one Japanese parent is automatically a Japanese national, regardless of the place of birth. Children born in Japan to parents who are stateless or have an unknown status may become Japanese nationals after three years of residence. Adopted children of Japanese nationals have a further reduced residence requirement of one year. Persons born to a Japanese parent and foreign national who are unmarried but acknowledged as their
natural children, or such parents who marry after birth, may acquire Japanese nationality by notification to the
Minister of Justice. Foreigners over the age of 18 (or age 20 prior to April 1, 2022) may become Japanese citizens by
naturalization after residing in the country for at least five years, renouncing any previous nationalities, and proving self-sufficiency through their occupation or existing financial assets. Applicants should be able to demonstrate elementary knowledge of the
Japanese language, though this is not a legal requirement. Japanese nationals who voluntarily acquire a foreign nationality automatically lose their Japanese nationality. Those who involuntarily hold a foreign nationality are required to choose between their Japanese or foreign status before the age of 22, or within two years of obtaining the other nationality if acquired after age 20. Dual nationals who fail to make this choice within the prescribed time period can be required by the Minister of Justice to provide a declaration of nationality within one month; further failure to state a choice of nationality results in automatic loss of Japanese nationality. Persons who were born in another country, acquired a foreign citizenship at birth, and chose not to retain Japanese nationality are regarded as having lost their Japanese status at the time of birth. ==Controversies==