Unpaid overtime is routine in factories and offices across Japan.

At Toyota, it had been built into factory life -- in the form of long, after-hours quality-control sessions that were supposedly voluntary -- and was considered a key to the company's success. Participation in the sessions, though, often figured in a worker's prospects for promotion and higher pay.

Toyota announced in May that it would begin paying overtime to workers who take part in the quality-control sessions.

McDonald's Japan, having lost a lawsuit to a restaurant manager who claimed his health failed because of long hours, announced in May that it, too, would pay more overtime.

In the wake of the case of the engineer who died after working night and day on the hybrid Camry project, Toyota said last week that it would try to improve its monitoring of workers' health.

Special correspondent Akiko Yamamoto contributed to this report.