Tadishi Ishii, CEO of Dentsu, ad/PR firm with $1.67 trillion in income and 47,300 employees, resigned Dec. 25 after 24-year-old Matsuri Takahashi committed suicide, claiming overwork.

Takashi cited workloads that lasted through the weekend and totaled more than 100 hours a month in overtime.

Matsuri Takahashi

Ishii told a news conference he was taking the suicide “seriously.” The company has started to turn off office lights at 10 p.m. as part of reforms.

A report of the Japanese Labor Bureau in October found that nearly a quarter of companies surveyed said some of their employees were putting in more than 80 hours of overtime monthly. The Bureau in October ruled the death of Takahashi was due to overwork.

The Bureau raided four Dentsu offices in October. It said the company was "cooperating fully" but attempts to address the culture of overwork were "superficial."

Takahashi was in the digital account division which was charged with "systematic overbilling and cheating of customers."

Dentsu PR is a small part of the parent, reporting $11 million in revenues and 243 employees for 2015. Young & Rubicam is Dentsu's U.S. advertising affiliate.

Dentsu PR, calling itself Japan's largest PR firm, in 2010 allied with the MSL Group of Publicis. However, Maurice Levy, Publicis CEO, said today the tie ended years ago. Publicis is celebrating its 90th anniversary this year. Dentsu has offices in the U.S. but no one could be reached today by phone or email.

Takahashi Tweeted Complaints

Takahashi tweeted that not only was she made to work too many extra hours but that she was bullied by her bosses who found fault with her work.

Tweets said bosses complained that she was coming to work with “messy hair and bloodshot eyes” and her appearance lacked “femininity.”

In one of her final messages before she jumped to her death from a Dentsu dormitory last Christmas, she tweeted, “They’re making me work Saturdays and Sundays again. I seriously want to end it all. It’s 4 a.m. and my body’s trembling. I'm going to die. I'm so tired."

The charges against Dentsu have been referred to the prosecutors office for alleged violations of the Labor Standards Act. A successor to Ishii is to be named in January. This is the first instance of a Dentsu executive resigning ahead of schedule in at least 40 years, said Japanese media. Criminal charges are possible against those involved, said media.