There are obvious differences between US and Japanese work culture. Firstly is the idea of individual vs collective mindset in the two societies. You tend to not think for yourself in Japan, but follow the protocol or hierarchy. You become a little soldier working toward the same goal. There is also the notion of getting a good job, perhaps even for life, and being treated well as long as you work hard. Training and upwards employment from within is still very important in Japanese culture.
In law there is a contracted 40 hour week the same as you might have in the US (also here in the UK), but in general if you work in a bigger city, a more prestigious job will be pressurised and with more responsibility, so people can often work 50 or 60 hours easily, the same as they might in similar jobs in the US or Europe. And forget taking your contracted time off, you get treated like a leper.
I think the idea of working less than 50 hours is a bit of a myth, truth be told. It is stressful to the point where it has become a national mental health crisis, and some people even die from exhaustion, which seems ridiculous in the 21st century. So I wouldn't say they do a good job with it, it's toxic on a human level. But as time progresses and young people fight against the old Showa era mindset, there has been some change with the government passing laws forcing companies to allot so many sick or vacation days to employees, to align more with the 40 hour contract, even some talk of certain companies trialling 4-day working weeks.