A transgender trade bureaucrat on Friday launched a landmark ¥18 million discrimination lawsuit against the government, claiming the trade ministry refused to let her use the female toilets and harassed her about her sex change.

The lawsuit, filed with the Tokyo District Court, exposed what the plaintiff called the bureaucracy’s lack of understanding toward sexual minorities and a failure by her employer, the Ministry of Economy, Trade and Industry, to honor its remit to promote diversity among all Japanese firms.

It marks the first time a transgender person has initiated legal action seeking to rectify discrimination at a workplace, her lawyers claimed.

“I am a woman. That’s what my identity is,” said the METI official in her 40s. “By fighting this legal battle, I wish to change society so that transgender people like me who are subject to unreasonable, subhuman treatment can enjoy rights to equality.”

After joining METI as a man fresh out of college, the official was diagnosed with gender identity disorder and began receiving hormone injections in 1998. The official formally began working as a woman in 2010, and changed her name in the family register in 2011.

Although permitting her to use the female locker rooms, METI remains opposed to her use of the female toilets on her floor on the grounds that her legal gender is still male.

The law stipulates a person must undergo what is known as gender reassignment surgery to physically change gender and thus their legal sex. But the surgery is extremely expensive, and some, including the plaintiff, cannot do it for health reasons.

METI suggested the plaintiff use the bathroom reserved for handicapped people — a proposal she has slammed as “unacceptable” because it amounted to segregation.

It also said that if any departmental transfer were to take place, it would require her to explain her condition to her new colleagues and “seek their understanding.”

Not doing so would mean she could not use the female toilets. “Forcing somebody to publicly reveal details about their disorder is an egregious human rights violation,” she said.

The plaintiff also claimed she suffered a mental breakdown and took a one-year leave of absence in February 2013 after receiving abusive remarks from her bosses that showed they had a serious lack of understanding toward diversity.

“If you don’t plan to have a surgery anytime soon, why don’t you get back to a man?” the complaint quoted one of her bosses as saying. “The rights of women are more important than that of people with a gender identity disorder,” another said, according to the complaint.