Journalist Miwa Sado died from karoshi, or death from overwork Credit:Screengrab ANN News via YouTube The determination that Sado's death was caused by overwork has brought renewed scrutiny to the working culture in Japan, where hundreds, if not thousands, of people are believed to work themselves to death every year. One NHK official told reporters that Sado's death was indicative of "a problem for our organisation as a whole, including the labour system and how elections are covered". Japan's working culture, where long hours and after-work social engagements are typical, dates back decades. "It began in the 1970s, when wages were relatively low and employees wanted to maximise their earnings," The Washington Post's Anna Fifield has reported.

"It continued through the boom years of the 1980s, when Japan became the world's second-largest economy and everyone was on the juggernaut. "And it remained after the bubble burst in the late 1990s, when companies began restructuring and employees stayed at work to try to ensure they weren't laid off. "Still, irregular workers - who worked without benefits or job security - were brought in, making the regular workers toil even harder. "Now, no one blinks an eyelid at 12-hour-plus days. " 'In a Japanese workplace, overtime work is always there. It's almost as if it is part of scheduled working hours,' said Koji Morioka, an emeritus professor at Kansai University who is on a committee of experts advising the government on ways to combat karoshi. 'It's not forced by anyone, but workers feel it like it's compulsory.' "

The country classified 189 deaths from overwork in 2015 - 93 suicides and 96 from heart attacks, strokes and other illnesses related to overwork - although experts believe the actual number might be much higher. In addition to long hours, holidays routinely go unused: on average, employees used less than half of their leave time in 2015 - about nine days a year, The Guardian reported. More than one in five Japanese employees work 49 hours or more each week. In Sado's case, 159 hours of overtime averages more than 5½ hours a day over the course of a 28-day month. The Asahi Shimbun newspaper reported that Sado was busy covering candidates and their supporters, shooting footage of speeches and attending meetings during the election. "She was under circumstances that she could not secure enough days off due to responsibilities that required her to stay up very late," said a release from labour regulators, the paper said.

"It can be inferred that she was in a state of accumulated fatigue and chronic sleep deprivation." Sado started work at NHK in 2005, when she was in her early 20s, the Japan Times reported. NHK said that it waited to make information about her death public out of deference to her family, reports said. "Even today, four years after, we cannot accept our daughter's death as a reality," Sado's parents said in a statement released by the broadcaster to Japanese media. "We hope that the sorrow of the bereaved family will never be wasted." The deaths of other young Japanese workers have brought renewed attention to the issue in recent years.

In 2015, the despondent messages left on Twitter by Matsuri Takahashi, a 24-year-old who was working more than 100 hours of overtime a month at an ad agency, drew wide attention after she killed herself by jumping from a company dormitory. "I'm going to die. I'm so tired," she wrote in one message. The company's president and chief executive later resigned, due in part to an outcry over her death. Later that year, 34-year-old maintenance worker Kiyotaka Seriwaza killed himself after putting in 90-hour weeks at a company from which he had tried, unsuccessfully, to resign. The government has been taking steps to change the culture around work to address the problem of karoshi, passing legislation in a bid to reduce the number of employees working more than 60 hours a week and to entice them to use their paid holiday time.

Early this year, a government spokesman told Bloomberg News that Japan needed to "end of the norm of long working hours so people can balance their lives with things like raising a child or taking care of the elderly". Companies have been joining the effort, taking steps to encourage workers to leave work, use their holidays and spend more time away from work. Dentsu has begun shutting the lights off in its headquarters at 10pm and now requires workers to take at least five days off every six months. Japan Post Insurance, a life insurance company, shuts off its lights at 7.30pm. Yahoo Japan has been considering a four-day work week. Sado had sent an email in the weeks before her death that warned of the toll her work was taking on her, the Shimbun reported.

"I am too busy and stressed out and think about quitting my job at least once a day, but I guess I have to hang on," she wrote. She was discovered in her bed, holding her mobile phone in her hand. Washington Post