LATE of an evening, Japan’s black-suited salarymen let their hair down in the streets of Shimbashi, a district of Tokyo. Shirts untucked, ties off, liquor flowing, they stagger around before heading home, or directly back to the office via a konbini (convenience store) to buy a clean shirt.

This is the harmless outlet for their stress: karoshi, or death by overwork, is the darker, and until recently, more overlooked one. This month the first ever government report into the scale of karoshi found that employees put in over 80 hours of overtime a month at almost a quarter of companies surveyed. At 12% of those firms the figure rose to a whopping 100 hours. These numbers may underestimate the problem; under a fifth of 10,000 companies contacted responded, which is a normal response rate, but firms with still worse overtime figures may have kept out of the study.

Little wonder that 93 people committed or attempted to commit suicide in the year to the end of March 2015 because of overwork. These are the cases where the government has officially recognised that families are owed compensation; activists against karoshi reckon the number is too low. Other workers perish from heart attacks or strokes due to long hours. The latest high-profile case is a 24-year-old female employee for Dentsu, a Japanese advertising giant, who committed suicide in December.

Things have got somewhat better in recent years; more overtime is paid, for example. But further steps are needed. Shinzo Abe, the prime minister, says that changing the working style in Japan is one of the main aims of labour reforms that he plans to introduce next year. Yuriko Koike, the new governor of Tokyo, wants to improve the city’s work-life balance and has banned workers in her office from staying past 8pm.

But it remains hard to overhaul business practices when the culture values face time and dedication to the job far ahead of performance. “The company is like a big team. If I leave work early, someone else has to shoulder my work and that makes me feel terribly guilty,” says a 42-year-old IT worker who preferred to remain anonymous. It does not help that the shrinking and ageing of Japan’s population means labour shortages. And all this overwork does little for the economy, because (thanks to the inefficient working culture as well as low use of technology) Japan is one of the least productive economies in the OECD, a club of rich nations, generating only $39 dollars of GDP per hour worked compared with America’s $62. So the fact that workers are burning out and sometimes dying is pointless as well as tragic.