TOKYO (AFP) - The news that a young reporter at Japan's public broadcaster had worked herself to death came as little surprise to those inside the country's media, where a culture of excessively long hours has become the norm.

"I thought it would happen eventually because we work like crazy... like a slave," said a journalist at one of Japan's major newspapers.

"I really thought I would die," she told AFP on condition of anonymity, recalling her days chasing after the prime minister and lawmakers in Tokyo, when she would routinely come home from work at 1.00 am and wake up four hours later.

While journalists tend to work long hours in many countries, the situation in Japan is among the most extreme, with reporters expected to be on the job 24-7.

The newspaper journalist - now in her 30s - was one of a gang of hardcore Japanese reporters who stake out the houses of politicians they were assigned to follow every single night whether there is news or not - a ritual called "Yomawari," meaning "night round".

Even on a snowy night, she used to wait hours outside the house of a politician she was covering.

"I had disposable hand warmers everywhere on my body but it was still too cold. I couldn't go to the bathroom. It's bad for your health," she said, adding that she's seen fellow journalists becoming physically and mentally ill.

And forget the weekend, she added, as political reporters chase lawmakers back to their constituencies on Friday night.

Related Story NHK apologises over death of young reporter who logged 159 hours of overtime

A former Tokyo TV reporter pointed the finger at the Japanese culture of "fighting spirit," in which you're told to never give up no matter what.

The 32-year-old, who was no stranger to working around the clock, remembers the day she kept going even though she felt seriously ill.

"I didn't have time even to check my body temperature. Later I realised I had a 39-degree fever," she said.

"Bosses would say you shouldn't be lazy but they wouldn't say you should get rest because you're working too hard."

"Then you become like a zombie... this has to stop."

The case of NHK reporter Miwa Sado, who died of heart failure aged 31 after logging 159 hours of overtime in the month before she died, made global headlines but was far from an isolated tragedy.

Every year in Japan, long working hours are blamed for dozens of deaths due to strokes, heart attacks and suicides.

Death from overwork even has its own word in Japanese - "karoshi".

According to a government report released last week, there were 191 "karoshi" cases in the year ending March 2017.

The report also showed that 7.7 per cent of employees in Japan regularly log more than 20 hours of overtime a week.

NHK journalist Sado, who had been covering Tokyo assembly elections and an upper-house vote for the national parliament, was found dead in her bed in July 2013, reportedly clutching her mobile phone.

She died three days after the upper-house election.

A government inquest a year after her death ruled that it was linked to excessive overtime. She had taken two days off in the month before she died.

NHK eventually made the case public four years later, bowing to pressure from Sado's parents to take action to prevent a recurrence.

It was especially embarrassing for NHK, which has itself taken aim at Japan's long-hours culture.

"I was shocked that someone at NHK, which has been campaigning against Japan's long working culture, died from overwork," said Shigeru Wakita, emeritus professor at Ryukoku University and an expert on labour law.

"Mass media should be able to change the habit of long working hours but they just don't," he told AFP.

NHK boss Ryoichi Ueda went to the house of Sado's parents to deliver a personal apology and vowed reform of the broadcaster's working practices.

The firm has pledged to reduce hours spent at work, introduce health standards and hold seminars to address the "karoshi" problem.

The case also attracted the wrath of the government, with Labour Minister Katsunobu Kato urging Japan's public broadcaster to reduce long working hours "so that such incidents will never happen".

The government itself has tried to clamp down on "karoshi", naming-and-shaming more than 300 companies in its first nationwide employer blacklist released in May.

In April, a government panel unveiled its first-ever plan to limit overtime - with a 100-hour-a-month cap, which sparked anger among critics and family members who lost their loved ones due to overwork.

Prime Minister Shinzo Abe has wrestled with the problem and introduced so-called "Premium Fridays", where employees are urged to knock off work early on the last Friday of the month.

Abe himself spent a Friday afternoon meditating in a bid to lead the way but critics slammed the plan, saying it was not compulsory with most firms simply ignoring it.

Wakita charged that the government is not being "serious enough" to tackle the issue.