Workers were dying and the language had no word for it, so three doctors invented one.
In 1969, a twenty-nine-year-old man working in the shipping department of Japan's largest newspaper company died of a stroke.1 He had been working excessive overtime with increasing workload and declining health. It took five years for his family to receive workers' compensation. At the time, his death was classified as "occupational sudden death." There was no specific word for what killed him.
In 1982, three physicians, Tajiri Seiichiro, Hosokawa Michio, and Uehata Tetsunojo, published a book titled Karoshi, creating the term that would define the phenomenon.2 The word combines ka (過, excessive), rō (労, labor), and shi (死, death). It is not a clinical diagnosis but a sociomedical category, linking cardiovascular death directly to workplace conditions.
The term gained broad public recognition in the late 1980s, during Japan's Bubble Economy, when several high-ranking business executives died suddenly without prior signs of illness.3
In 1988, the Labor Force Survey reported that almost one-quarter of male working employees were logging more than sixty hours per week.1 That same year, the Karoshi Hotline was established and received its highest-ever volume of calls in its first two years of operation.
In South Korea, the equivalent term is gwarosa (過労死). In China, the phenomenon is described by the term guolaosi. The International Labour Organization includes long working hours, shift work, and excessive overtime among the occupational risk factors for karōshi.4 In 2008, a key Toyota engineer's death was ruled karōshi after records showed he had averaged more than eighty hours of overtime per month.3