The parents of a 27-year-old former part-time city worker who committed suicide in 2015 filed a lawsuit Tuesday demanding ¥13 million in compensation from the Kitakyushu Municipal Government, claiming their daughter was overworked and harassed by a supervisor.

Kana Morishita's parents say she took her own life after being harassed by her superior and that the city should also give its part-time workers the right to file compensation claims.

Their attorney, Sachiyo Tsukuda, said many local governments, except for the Tokyo Metropolitan Government and some others, do not allow part-time employees to seek compensation.

"We hope this lawsuit will help revise the workers' compensation system in local governments nationwide," Tsukuda told a news conference after filing the lawsuit.

"I hope the working environment for part-timers will be improved so there will never be any more victims like her," Morishita's 55-year-old mother, Mayumi, said.

According to the petition filed with the Fukuoka District Court, Morishita had been working at the Tobata Ward Office in Kitakyushu since 2012, giving advice to people having problems raising children. She suffered depression in January 2013, quit work in March that year and committed suicide in May 2015.

Her parents attributed her death to an excessive work burden and harassment by her superior and tried to ask for workers' compensation, but the municipal government denied the claim, saying neither part-time workers nor their next of kin have the right to pursue such redress.

The city said it investigated the harassment allegations at the request of the victim's parents but found no proof to substantiate the claim, thus judging that the suicide was not a work-related accident.