The labor ministry is making arrangements to refer the Dentsu advertising agency and officials at its branch offices to prosecutors for allegedly making employees work illegally long hours, according to sources close to the matter.
The ministry's Tokyo Labor Bureau has already pursued Dentsu's violation of the Labor Standards Law over the overwork-related suicide of a 24-year-old employee. It is now investigating whether other employees were made to work illegal amounts of overtime.
The ministry appears to be struggling to find evidence clearly proving that senior officials of the nation's biggest advertisement agency were aware of the alleged illegal conduct, the sources said Monday, adding it is expected to decide whether to pursue the case by the end of the month at the earliest.
Officials at Dentsu branches in Nagoya, Osaka and Kyoto are also suspected of violating the Labor Standards Law.
Dentsu's head office in Tokyo and the branch offices in Osaka and Nagoya were warned by local labor authorities to address long working hours in 2015, 2014 and 2010.
The government is stepping up efforts to curb excessive work hours after labor authorities determined last September that Matsuri Takahashi, the 24-year-old Dentsu employee who committed suicide in December 2015, had died from overwork.
The case of karoshi (death from overwork) caused an uproar over excessive working hours at leading companies.
Takahashi was reportedly working 105 hours of overtime per month — far in excess of the 70-hour limit set in a labor-management agreement — before she developed symptoms of depression.
Dentsu reached an agreement with her family Jan. 20 to take measures to prevent a recurrence and pay money in settlement.