http://edition.cnn.com/2016/12/06/world/pisa-global-education-rankings/index.html
It will be true that Asian's high performance on PISA derives from hard work. But, there is a question that hard work is not common in rest of the world.
Here are some reasons
http://www.speeli.com/articles/view/Why-do-asians-work-very-hard
In summary, working hard is a culture.
What kind of culture drives them into working hard?
Difficulty to learn language(Especially Chinese characters) would be a reason. It must have brought the impression that to achieve something needs to study hard.
