A Japanese man in his early forties — let’s call him a salaryman at a major Tokyo company — has been working roughly 80 hours a week for the past several months. He sleeps four or five hours a night, eats most meals at his desk, hasn’t taken a vacation day in over a year. On a Wednesday morning, after attending a long meeting, he collapses at his desk. He is taken to a hospital and dies hours later. The cause is recorded as cardiac arrest. His family files for recognition that the death was caused by overwork. After three years of administrative review and litigation, it is granted.
This is karoshi — death from overwork — and the fact that Japan has a specific word for it is information about the structure that produces it. The phenomenon is real, statistically tracked, legally adjudicated, and the subject of decades of attempted reform. Most cultures don’t have a single word for “death by working too much.” Japan has one, and the existence of the word both names a problem and gestures at the work culture that, in extreme cases, can kill the people inside it.
This article describes a difficult social phenomenon. It is intended as cultural and structural explanation, not as personal commentary on any individual case. If you are working under conditions that feel unsustainable, please consider consulting a labor attorney, a medical professional, or appropriate workplace resources.
What the word literally is
過労死 (karoshi) reads as karou (overwork, fatigue from excessive labor) + shi (death). The compound is direct: “death from overwork.” The word entered widespread use in Japan in the late 1970s and early 1980s, coined by labor lawyers and journalists as they began to identify a pattern of sudden deaths and suicides among heavily overworked employees.
The Japanese government formally recognized karoshi as a workplace health issue starting in the 1980s, with diagnostic criteria refined over subsequent decades. The Ministry of Health, Labour and Welfare maintains official statistics on recognized cases. The Industrial Accident Compensation Insurance system provides benefits to families of officially recognized karoshi victims.
Two related terms exist in Japanese:
Karoshi — physical death (cardiac arrest, stroke) attributed to overwork.
Karou-jisatsu (過労自殺) — suicide attributed to overwork; sometimes counted under the karoshi umbrella, sometimes treated separately.
Both are recognized causes for compensation claims, though the bar for legal recognition is high.
The diagnostic criteria
For a death to be officially recognized as karoshi, several elements typically must be established:
Excessive working hours. The threshold has shifted over time. Currently, official guidelines treat over 100 hours of overtime in the month preceding a stroke or heart event, or over 80 hours of overtime per month sustained for 2–6 months, as significant indicators of work-related causation.
Causal link to a recognized health event. Cardiac arrest, stroke, severe stress-related illness — for physical karoshi. Mental health deterioration leading to suicide — for karou-jisatsu.
Documented work patterns. Time records, witness testimony, electronic logs, often the subject of lengthy investigation since employers may not maintain accurate overtime records.
The legal process for getting a death formally recognized as karoshi can take years. Families pursuing recognition typically work with specialized labor attorneys; many cases are denied initially and pursued on appeal. The bureaucratic difficulty is itself part of the broader phenomenon.
The numbers
Officially recognized karoshi cases run to several hundred per year in Japan. The Ministry of Health, Labour and Welfare’s annual reports document numbers in the low to mid hundreds — typically 150–300 deaths per year in recent years across the karoshi and karou-jisatsu categories combined.
These are the officially recognized cases. Researchers and labor advocates argue the actual number is meaningfully higher. Many deaths plausibly attributable to overwork never enter the recognition system — the family doesn’t pursue the claim, the employer disputes the working hours, the diagnostic threshold isn’t quite met, the death is recorded as a generic cardiac event without further investigation. Estimates of the “true” karoshi count, depending on methodology, range from several hundred to a few thousand per year.
The numbers should be read alongside the broader Japanese workforce of roughly 67 million employed people. Karoshi affects a small percentage in absolute terms — but the existence of any such percentage from work-related causes is the cultural concern. Most other developed countries don’t measure or recognize the category.
The contributing structure
What makes Japan’s work environment particularly susceptible to extreme overwork is a constellation of factors, most of which are familiar inside Japanese workplaces but less visible from outside:
Implicit overtime norms
Japanese workplace culture has historically expected employees, especially in white-collar roles, to remain at work until the manager leaves. Leaving on time, even after completing your work, has been associated with insufficient dedication. This produces structural pressure to remain at the office, often performing minimal additional work, simply to avoid being seen as the first to leave.
Underreported hours
Many Japanese workplaces have historically treated official overtime records as separate from actual hours worked. “Service overtime” (service zangyou) — unpaid, unrecorded extra hours — has been common. Workers might clock out at 7 p.m. and continue working until 10 p.m. with the time uncompensated and undocumented.
Vacation reluctance
Japan’s annual paid leave is legally protected at 10–20 days for most employees, but actual usage rates have historically been low — Japanese workers take only about half their entitled leave. The reluctance to use vacation comes from both implicit social pressure (taking time off is read as letting the team down) and lack of replacement coverage during absences.
After-work obligations
Work doesn’t end when the office closes. Drinking with colleagues (nominication), client entertainment, weekend client visits — all are common, sometimes effectively mandatory, additions to the workweek. The total time spent on work-related activities can be substantially higher than the official working hours.
Lifetime employment expectations
The traditional Japanese employment model — joining a company immediately after university and staying for one’s entire career — created strong incentives to absorb extreme working conditions rather than leave. Quitting was professionally costly; refusing overtime was risky to career advancement. These structures are weakening in modern Japan but were historically powerful.
The reform attempts
Japanese government and major employers have made repeated attempts to address karoshi over the past several decades. Notable initiatives include:
1992 — establishment of the Karoshi Hotline, a phone line for families dealing with overwork-related health issues.
2000s — increasing legal recognition of karoshi cases and expansion of compensation eligibility.
2014 — the “Promotion of Preventive Measures Against Karoshi Act,” a national law specifically targeting overwork-related deaths.
2019 — work-style reform legislation introducing legal caps on overtime (100 hours/month maximum, 720 hours/year), with criminal penalties for violations. These caps remain higher than in many other developed countries but are the first hard legal limits Japan has imposed.
Premium Friday — a 2017 government initiative encouraging companies to let employees leave early on the last Friday of each month. Adoption rates have been low; the initiative is widely considered to have failed.
Some changes have been visible — particularly in younger workers’ increasing willingness to refuse uncompensated overtime, in companies with stronger HR oversight, and in industries (especially tech) with international workforce comparisons. The traditional salaryman culture has weakened. But the structural pressures producing karoshi haven’t disappeared.
The 2015 Dentsu case
One case that drove significant public attention to karoshi: Matsuri Takahashi, a 24-year-old new employee at the major advertising agency Dentsu, who died by suicide on Christmas Day 2015 after months of severe overwork. Investigation showed she had worked over 100 hours of overtime in the month before her death. Her social media posts during the period documented her exhaustion and despair.
The case was extensively covered in Japanese media, contributed substantially to the 2017–2019 work reform legislation, and produced significant criminal and reputational consequences for Dentsu. The visibility of a young, recent-graduate woman dying from overwork at one of Japan’s most prestigious companies put a face on a phenomenon that had previously been more abstract for many readers.
What’s changing
Several trends are slowly shifting Japan’s overwork culture:
Younger workers are more willing to refuse unpaid overtime and to leave employers who require it. Work-from-home practices, accelerated by the pandemic, have weakened the “stay until the manager leaves” norm. International companies operating in Japan typically operate with hour limits closer to global norms, exerting competitive pressure on Japanese-style workplaces. Major Japanese companies have begun publicly tracking overtime statistics, both as legal compliance and as a recruiting differentiator.
The shift is incomplete. Karoshi cases continue. The deepest cultural patterns — the implicit expectation of total dedication, the difficulty of refusing overtime in some industries, the limited use of paid leave — change slowly. But the trend is toward improvement.
The principle underneath
What karoshi reveals, looked at carefully, is what happens when a culture’s work ethic operates without effective institutional limits. Japan’s work culture has historically produced extraordinary economic output, world-class quality across many industries, and a workforce capable of sustained focused effort. The same set of cultural features — dedication, group loyalty, deference to seniority, sustained effort — has, at the extremes, also killed people.
The fact that Japan has named the phenomenon, recognized it legally, tracked it statistically, and attempted reform is itself meaningful. Most cultures with extreme work cultures do not name what their work culture costs in human lives. Japan, having paid the cost long enough that the pattern became visible, named it explicitly — and the naming made the problem something that could be discussed, measured, and slowly addressed.
For a non-Japanese reader, karoshi is worth understanding for two reasons. First, it is a real Japanese social and labor phenomenon affecting hundreds of families per year and the focus of ongoing reform. Second, the conditions that produce it — implicit overtime norms, vacation reluctance, after-work obligations, employer-employee power imbalances — are not unique to Japan, and the Japanese conceptual vocabulary for talking about them is one of the more developed in the world. Some of the words a culture builds are for what its strengths produce when those strengths run unchecked. Karoshi is one of those words.