Hundreds of members of the gay, lesbian, bisexual and transgender community filed an unprecedented request Tuesday with the Japan Federation of Bar Associations (JFBA) in a bid to legalize same-sex marriages, saying Japan's failure to recognize the practice constitutes a violation of human rights.

Coming on the heels of what lawyers behind the move called a gradual softening of traditional prejudice toward gays in Japan, the bid by 455 individuals is the first attempt to legalize same-sex marriages by appealing over human rights.

The JFBA, the nation's biggest bar association, will investigate the allegation and, if necessary, issue a warning to the central government to review its approach toward the matter.