The Japanese government has recently taken measures to address the issue of overwork

A woman in Japan died from overwork after logging 159 hours of overtime in the month leading up to her death, labour inspectors have ruled.

Miwa Sado, a political journalist at the country’s national broadcaster, suffered heart failure in July 2013, though her employer only made the case public this week.

Officials in Tokyo deemed the 31-year-old had died from karoshi – death from overwork – after taking just two days off in the 30 days before she died, reports The Japan Times.

Masahiko Yamauchi, a senior official at the broadcaster, said Ms Sado’s death was a “problem for our organisation as a whole, including the labour system and how elections are covered”.

In a comment released by NHK, her parents said: “Even today, four years after, we cannot accept our daughter’s death as a reality.

“We hope that the sorrow of the bereaved family will never be wasted.”

In 2015 the suicide of an advertising agency employee, who was working 100 hours overtime a month, prompted calls for a shift in Japan’s work culture.

According to a national survey, a fifth of the country's workforce are at risk of karoshi, since they clock more than 80 hours extra work time each month.

The Japanese government has recently taken measures to address the issue.

In February it launched a campaign urging employees to leave early at 3pm on the last Friday of every month, and in May it named and shamed more than 300 companies that had breached labour laws.

Independent News Service