Karoshi - Japanese Management Syndrome

Understanding Karoshi

As a distinctively Japanese business practice, Karoshi¹ (death from overwork) is one of the most internationally recognized terms associated with Japan, alongside Kaizen. In June 2014, Japan enacted the Act on Promotion of Measures to Prevent Death and Injury from Overwork, leaving many observers overseas with the plain shock that “people in Japan die from working too much, and a dedicated law has been created to address it.” Under this law, the government publishes annual white papers and tracks the issue over time.

As of 2026, Karoshi is not clearly moving toward resolution. The most recent trend is upward. During this period, Japan has been able to reduce long working hours in part statistically, but it has not been able to control the final outcome.

Karoshi spreads worldwide

The core of Karoshi is understood as cerebrovascular and cardiovascular disease associated with long working hours. It is tracked separately from Karojisatsu, or suicide from overwork, which is an extension of deteriorating mental health.

Japan, where the concept originated, identified the basic research framework for the harmful health effects of long working hours in the 1960s and also took the lead in establishing social systems that treat the issue as an occupational injury.

Then, led by the WHO Global Plan of Action on Workers’ Health (2008–2017), similar academic research was conducted on occupational diseases worldwide.
Several large-scale studies have confirmed the following results.

These findings made clear that the largest cause of work-related death, even globally, is indeed long working hours.
In recent years, the WHO and ILO have begun monitoring trends in long working hours across countries and issuing recommendations.

Reinterpreting secondary factors through medical guidelines

There is no doubt that long working hours increase the risk of cerebrovascular and cardiovascular disease, but the pathway is also strongly affected by lifestyle factors. From the standpoint of self-protection, knowledge of these secondary factors is also useful.

Medical guidelines on cerebrovascular and cardiovascular disease regard these conditions as arising against a background of chronic vascular abnormalities and identify hypertension, diabetes, dyslipidemia, and smoking as major risk factors⁶.

When considering death and illness, it is important to focus on chronic deterioration in diet—such as excessive salt, sugar, and fat—as well as alcohol consumption and smoking. These are considered preventable factors. Chronic vascular inflammation caused by salt and the accumulation of LDL cholesterol can age the blood vessels far beyond what would be expected for one’s chronological age.

Because long working hours and lifestyle-related disease coexist in many real cases, many physicians would probably first say that, as a feasible intervention, “dependence on fast food, eating out, convenience-store boxed meals, and izakaya meals must be controlled.”

There are reasons this is difficult to implement. In practice, following a physician’s advice requires attention to ingredients and cooking at home. Eating out often tends to mean excessive salt intake in any case.

Even so, when the issue is considered as a whole, a healthy diet is indispensable.

The Japan-specific element remains

The typical story of Karoshi is that after a long period of excessive working hours, a person suddenly collapses at work, is transported to a medical institution, and dies from a stroke or myocardial infarction.
Employees collapse at work outside Japan as well, and such cases are investigated as occupational safety issues. In many cases, however, they are likely classified as individual illness.

In reality, Japan has a background in which long working hours remain deeply entrenched.
The Karoshi white paper recognizes that the share of workers exceeding 49 hours per week is notably high among men in Japan, at 20.4%, compared with Western countries such as the United States (15.3%), the United Kingdom (12.5%), France (10.9%), and Germany (6.4%)⁷.

This shows that working hours exceeding the WHO/ILO threshold of 55 hours per week remain far from rare in Japan.

When converted into the standard more commonly used in Japan, 55 hours per week corresponds to 65 hours of overtime per month.

Although the general rule limits overtime to 45 hours per month, as noted above, about 20% of men exceed this level, so it cannot be regarded as a threshold that functions as a real prohibition. In addition, workers’ compensation recognition is concentrated around 80–100 hours of overtime per month.

Japan exported the concept of Karoshi, showed the world the dangers of long working hours, and contributed to the WHO-led scientific estimation of risk thresholds. Yet Japan has not reimported these new findings.

Actual risk increases long before the question of whether workers’ compensation is paid, so regulation centered only on extremely long working hours is structurally unlikely to reduce Karoshi.
Because these diseases have the property that risk rises gradually, from the perspective of effectively preventing Karoshi, 49 working hours per week should be treated as a hard limit.

The problem of long working hours

There are two major problems with long working hours.

The first is that the cost of additional labor is broken. Discretionary labor systems have been identified as fertile ground for long working hours.

As an obvious premise, contractual conditions in which there is no pay for time under employer control cannot be valid. This is illegal in Japan as well, but the government has been trying to control not only working hours but also unpaid overtime, which remains deeply rooted in practice. In 2024, the Labor Standards Inspection Offices reported that they had instructed 11,230 workplaces to correct illegal overtime work⁸.

The more fundamental problem is that many Japanese people regard long working hours as necessary. Although this is precisely the point that people outside Japan are known to criticize as crazy, it has never really been corrected.

Outside Japan and parts of East Asia, workers in other countries generally do not accept long working hours that greatly exceed their contractual obligations in the first place. From the standard global perspective, no further explanation is needed. Japanese people, however, have many accompanying narratives about “why long working hours are necessary.”

Japanese Management Syndrome

At the root of Japan’s distinctive pathology is a category error: trying to solve every problem through process improvement.
The Kaizen of “Japanese management” reproduces Karoshi⁹.

At workplaces where Karoshi occurs, the work is already not going well at the warning-sign stage.

When work is not going well, Japanese people ask, “How can we make this work?” The instruction from a superior is, “Think about how to make this work.”

When a task requires five hours but the available working time is only one hour, the task cannot be executed. Yet if the working time is one hour and the deadline is the next morning, that task often becomes possible in Japan. In countries outside Japan, anyone faced with such work would get angry and refuse. That natural response is broken in Japan.

In this example, there is room for the work to be completed with a partial dose of Karoshi, but of course some work cannot be completed, and some work has a low probability of success. In those cases, the work fails. The standard global response to failing after making sacrifices would be to increase the level of anger. In Japan, however, this form of failure is often interpreted as a better effort.

The greatest problem with the absence of refusal before work begins is that it creates a bias in which failures during execution increase, making it seem as if process improvement can raise the probability of success. Those who accept unfavorable work also end up playing a role in strengthening the Karoshi mechanism.

The reason the concept of Karoshi emerged by directly linking many causes of cerebrovascular and cardiovascular disease to companies is that many businesspeople resent this structure.

The need to recover a resource-allocation perspective

The essence of Japanese management is non-management. The core function of management is resource allocation, but Japan does not look at the validity of its resource allocation.

If the main management issue is understood as “development is not progressing as expected,” then it is time to revise that view. In recent years, academic research has reached agreement on general cognitive ability and confirmed that no training can produce effects such as “developing the ability to think.” Research on strengthening cognitive ability began in the late nineteenth century, but expectations that the intellectual ability of healthy adults can be improved have now come to an end.

At the same time, research on personality traits has made rapid progress, and it has become clear that a company’s capabilities are determined to a considerable extent by the selection of managers based on personality.

By conducting internal personality analysis based on the scientifically standard Big Five, companies can build a database for personnel selection. This is like identifying one’s current location with GPS instead of trying to find a destination using only a map. Decider provides Big Five analysis that companies can use easily.

When these findings are considered together, “How can we make this work?” should be treated not as a question for frontline employees, but as the role of managers. People must have already noticed that the conditions were infeasible. Work that has no chance of succeeding should simply be abandoned before it begins.

If this alone were enforced thoroughly, Japan would behave like other countries, and Karoshi should disappear.

Naturally, managers need the ability to think, and because this is a stable trait that does not change, trial and error through reassignment becomes necessary.

Now that we know development in this sense is an illusion, this does not mean past development was wasted. If things are not working, there is an opportunity to appoint a different manager.

This article has omitted discussion of Karojisatsu, but anyone who reads the white paper on measures to prevent death and injury from overwork will quickly see that the behavior of managers is a major problem.

Japanese people have continued to misperceive the issue, but this is precisely what businesspeople around the world have been criticizing.