TOKYO — He sits in an office of a major Japanese sportswear maker but reports to no one. He is assigned odd tasks like translating into English the manual on company rules like policies on vacations and daily hours, though he has minimal foreign language skills.

He was sidelined, he says, as retribution for taking paternity leaves after each of his two sons was born. Now he’s the plaintiff in one of the first lawsuits in Japan over “pata-hara,” or paternity harassment, as it is known here. The first hearing is scheduled for this week.

His case is unusual in a country that values loyalty to the company, long hours and foregone vacations, especially from male employees. He asked not to be named for fear of further retribution.

The man, whose sons are now 4 and 1, was initially assigned to a sales-marketing section at Asics, where he rubbed shoulders with athletes, but was suddenly sent to a warehouse after his first paternity leave in 2015, according to his lawsuit.

After he hurt his shoulder, he was assigned to the section he is in now, where he says he is forced to sit and do little.

He wants his original assignment back and 4.4 million yen ($41,000) in damages.

Asics said it plans to fight the allegations in court, adding that it was “regrettable” no agreement could be reached despite repeated efforts.

“Our company remains committed to pushing diversity, and we plan to foster a work environment and support system so all workers can stay productive during pregnancy, childbirth and child-rearing,” it said in a statement.

Makoto Yoshida, professor of social studies at Ritsumeikan University, believes acceptance of paternity leave will take decades in Japan because it goes to the heart of corporate culture, which includes not being able to refuse transfers.

“A boss is apt to think a worker who takes paternity leave is useless. The boss is likely never to have taken paternity leave himself,” Yoshida said. “And once an office sees a worker getting bad treatment for taking paternity leave, no one else is going to want to do it.”

Japanese law guarantees both men and women up to one year leave from work after a child is born. Parents aren’t guaranteed pay from their companies, but are eligible for government aid while off.