Death by overwork is called karoshi. Japanese salarymen will often stay at work until 10pm or so. Then it is expected of them to hit the bars with their co-workers until midnight, then come right back to work at 8am the next day.
For a female to die that way is rather unusual, as the large majority of salarymen are male.
I was trained that you cannot work a man to death, they always pass out first.