I'm in the Netherlands and most days I work 8 or maybe 9 hours (5 days/week). There are a few dozen days per year when there are deadlines looming and it's more like 11-12, or in the weekend. But that's both person and company dependent.
But actual programming is not 8 hours. There's programming-related stuff that's not quite programming, like waiting for compiles, doing reviews, making estimates, answering questions, courses. And there are things like meetings and toilet/coffee breaks. If I spend 5 hours actually programming, it's a good day.
I'm not familiar with Japan, but I've been to China a number of times. I admire the diligence, and understand that most people don't really have a choice. But my strong feeling is that it's really not productive - people just get too tired to work productively and to prevent mistakes. That's also backed by research, btw.
So, if you have any choice, I'd advice to work less, you'll probably get the same done, if not more. But good luck convincing your boss to give up decades of cultural interia...