The Tokyo High Court on Tuesday overturned the recognition of Japanese nationality given to an 8-year-old boy born out of wedlock to a Filipino woman and a Japanese man who, after the child was born, admitted fathering him.

The high court said that even if the Nationality Law provision, which mandates different treatment for children born to married couples and those born out of wedlock, was ruled unconstitutional, it would not enable the boy to gain Japanese nationality under the current system.

The Tokyo District Court declared last year that it was unconstitutional for the government to deny nationality to the boy, who was born out of wedlock and later recognized by his Japanese father.

A lawyer for the boy -- who lives in the Kanto region and is a second-grader -- vowed to take the case to the Supreme Court.

After arriving in Japan in 1992, the boy's mother became acquainted with his father, who was married to another woman, and gave birth in 1997. The father filed recognition papers in 1999.

Last April 13, the district court ruled it was unreasonable not to grant the boy Japanese nationality just because his parents are unmarried and said the Nationality Law provision violates the principle of equality before the law under the Constitution.

A child of mixed parentage born out of wedlock can obtain Japanese nationality if the parents marry after the birth or if the Japanese father acknowledges the child before birth, but not afterward.