In the Japanese language gambaru means "trying one's best," but might be better understood as "working like crazy." And this doesn't necessarily mean that you worked well, were successful or that you arrived at some breakthrough - it simply means that in Japanese business culture you threw yourself into the task like a fire man confronting a burning home.
Japanese group behavior certainly influences how people behave socially, and in the world of Japanese salarymen (business men), nothing is more valued than gambaru. Toshiya Enomoto writes on Japan and work:
"Even if they fail to get results, Japanese find much comfort in the act of trying. So much so that they see it as a virtue in and of itself. Some put so much effort into 'trying ' that they have little energy left for the task at hand."The image of the overworked, bone-tired Japanese salaryman is not a myth; I stayed at a home in Kobe, Japan where the husband routinely came home from work at midnight! And it was up and out the door at the crack of dawn the next day! (It's worth noting that he sleeps all day on Sundays).
It would be very difficult in Japanese business etiquette for a man to look at his watch, see that's it 6 pm and say to his colleagues: "Okay, I'm done. Time to see the wife and family." It's probably fair to say that workers and work in Japanese culture might be more efficient if they knew they could work like crazy for eight hours, and then go home.
This gambaru culture so dominates Japanese business culture, that some companies are forcing employees to leave the office at 7 pm so that they can go home, be with their wife and family and perhaps help the declining Japanese population.