## Facts

- A young employee joined Dentsu Inc. after university and was assigned to the Radio Promotion Division, handling substantial client-facing advertising work.
- Company rules set standard hours and purported overtime limits, but the workplace practice involved chronic late-night and all-night work and frequent under-reporting of overtime.
- Over time, the employee’s health deteriorated, with signs consistent with depression, including severe fatigue, insomnia, and mental distress observed by family members.
- In August 1991, after prolonged overwork, the employee died by suicide.
- The employee’s parents, as heirs, brought a civil damages action against Dentsu alleging breach of the employer’s safety duty and employer tort liability under the Civil Code.
- The Tokyo District Court found Dentsu liable and awarded substantial damages; the Tokyo High Court affirmed liability but reduced damages by assigning significant comparative fault to the employee and the employee’s mother.
- Dentsu appealed to the Supreme Court; the parents cross-appealed the apportionment of fault and damages.

## Issues

1. Whether an employer’s duty of care includes managing working conditions to prevent mental illness caused by excessive fatigue and stress, and resulting suicide.
2. Whether suicide following work-induced depression can fall within the scope of harm attributable to the employer’s breach, including where the final act occurs outside active work performance.
3. When, if at all, comparative negligence principles permit reducing damages based on the employee’s characteristics or the family’s conduct in a work-induced depression suicide case.

## Decision

- The Supreme Court dismissed Dentsu’s appeal, affirming employer liability for breach of the safety duty leading to depression and suicide.
- The Court partially reversed the Tokyo High Court’s damages apportionment, concluding that Dentsu bore greater responsibility than the High Court assigned.
- The case was remanded for recalculation of damages consistent with the Supreme Court’s limits on comparative fault in this context.

## Legal Principles

- Employers have a duty to organize and manage work—including working hours and workload—to protect employees’ physical and mental health from harm caused by excessive fatigue or stress.
- Where chronic excessive overtime foreseeably contributes to depression and suicide, employer liability may attach because the illness can impair judgment and link the suicide to the breach.
- Liability is not confined to harm occurring during a discrete task; it may extend so long as the employee’s conduct remains within the normal range of behavior connected to work-induced conditions.
- Comparative fault reductions in suicide cases require caution where the victim’s mental state is materially impaired; assigning major fault based on “character” or similar factors is generally improper absent demonstrably abnormal circumstances supporting such attribution.

## Conclusion

The Supreme Court reaffirmed and expanded employer responsibility for overwork-related mental injury by treating suicide following work-induced depression as a foreseeable consequence of inadequate work-time and workload control, and it restricted the use of comparative negligence to substantially discount damages in such cases.


Kono v. Dentsu Inc., 1707 Hanrei Jiho 87 (Japan 2000)