Japan has again been forced to confront its work culture after labour inspectors ruled that the death of a 31-year-old employee of the country’s public broadcaster, NHK, had been caused by overwork, the Guardian reports.

Miwa Sado, who worked at the broadcaster’s headquarters in Tokyo, logged 159 hours of overtime and took only two days off in the month leading up to her death from heart failure in July 2013.

A labour standards office in Tokyo later attributed her death to karoshi (death from overwork) but her case was only made public by her former employer this week.

The announcement comes a year after a similar ruling over the death of a young employee at Dentsu advertising agency prompted a national debate over Japan’s attitude to work-life balance and calls to limit overtime.

Matsuri Takahashi was 24 when she killed herself in April 2015. Labour standards officials ruled that her death had been caused by stress brought on by long working hours. Takahashi had been working more than a 100 hours’ overtime in the months before her death.

The government proposes to cap monthly overtime at 100 hours and introduce penalties for companies that allow their employees to exceed the limit – measures that critics say still put workers at risk, the Guardian reported.

More than 2,000 Japanese killed themselves due to work-related stress in the year to March 2016, according to the government, while dozens of other victims died from heart attacks, strokes and other conditions brought on by spending too much time at work.

Research shows that Japanese employees work significantly longer hours than their counterparts in the US, Britain and other developed countries. Japan’s employees used, on average, only 8.8 days of their annual leave in 2015, less than half their allowance, according to the health ministry. That compares with 100% in Hong Kong and 78% in Singapore.

Sado, a political reporter, covered the Tokyo metropolitan assembly elections and national upper house elections in June and July 2013. She died three days after the upper house elections.