Matsuri Takahashi was just 24 years old and the graduate of prestigious Tokyo University when she leaped to her death from her company dormitory on Christmas Day last year.

Tokyo Labor Bureau investigators ruled her suicide karoshi — death by overwork.

The Labor Bureau announced on Oct. 7 that Takahashi had been required to work 100 hours or more of overtime per month for months on end at the prominent Dentsu advertising agency. She often got as little as two hours of sleep a night, rarely had a day off and was ordered by supervisors to report fewer hours than she actually worked.

It’s an all-too familiar story in Japan, where employees at nearly one in four companies are at risk of dying from working too many hours, according to a government report issued last month.

But Takahashi’s case has struck a nerve in Japan, and could help hasten reforms that experts say are long overdue.