At least six transsexuals nationwide filed requests with family courts to legally change their registered sex Friday, the same day legislation allowing them to do so took effect.
The legislation allows people who have been diagnosed with gender identity disorder and undergone sex-reassignment surgery to change the sex recorded in the family register.
People who are married or have children are not eligible, however.
The law was enacted in the regular Diet session last year after a decade of campaigning by people who have had sex-change operations. The discrepancy between their physical appearance and registered sex causes them problems and often humiliation in their daily lives.
Psychiatrists estimate there are several thousand people in Japan who have the disorder.
At Tokyo Family Court in Chiyoda Ward, four transsexuals, including Masae Torai, 40, who has led the campaign for the legislation, filed requests to change their registration.
Torai was born a woman but underwent a sex-change operation in 1987. He said Friday's move marked a "fresh start" in his life and hoped that the court process to change his sex in the family register would be smooth.
"It will be great if I no longer need to explain (the reason for the difference between my appearance and official sex) at hospitals or other situations," Torai said, adding that at least three more people plan to file similar requests next week.