A 50-year-old female office worker from Yamaguchi Prefecture who took just four days off in six months before her death in 2015 has been recognized by labor authorities as a victim of karoshi, or death from overwork, a lawyer for her bereaved family said.

The Yamaguchi Labor Standards Office recognized the death of Tomomi Saito, of Hofu, Yamaguchi Prefecture, as karoshi in February in view of her extremely limited days taken off. This recognition came despite her overtime figures having not hit official thresholds.

A death is likely to be considered the result of overwork if an employee worked 100 hours or more of overtime in the previous one-month period, or 80-plus hours of overtime in at least two straight months in the previous six months.

Saito died of suspected heart disease at her home in November 2015, the lawyer, Tadashi Matsumaru, said Friday, arguing that the cause of her death was accumulated fatigue from overwork at a lunchbox sales firm.

Saito's overtime figure was about 70 hours in the month before her death and ranged from 71 to 77 hours each in the five months prior. However, Saito had taken just four days off in the six months leading up to her death, including one stretch where she worked 91 days in a row.

Her family applied for compensation from the government last November, saying that although her overtime came in under the official threshold, her days off had been too few.

Death from overwork has been a hot topic in Japan in recent months after the much publicized case of a 24-year-old female employee at advertising giant Dentsu Inc. whose suicide was recognized as a result of excessive working hours.