Not sure if you are referring to the United States when you say "my country," but we certainly have unpaid overtime. It's called a salary...In most cases you are expected to to work over time there, or really whatever it takes to get the job done. I know that when my father was working her worked about 50-55 hours a week normally and my girlfriend who is a middle school teacher between actually teaching, lesson planning, and grading works about 60 hours a week. I certainly don't like Japan's work culture, but their overtime policy doesn't seem that insane.
From my understanding this was brought in to law after WWII when Japan was under US occupation. I don't know the reason the law was enacted, but it was. Lots of people find this law to be terrible, but the problem is that no one is willing to bring it up or challenge it. They don't want to be the politician that want to change the censorship law.