[patio11]

I have a joke about this which is reasonably descriptive of the mechanism: Japan has a 45 hour work week. Men work 80; women work 10.

(If you prefer the non-joking version you can Google for social science research in Japanese or English; eyeballing the graph here should quickly confirm the impression "Oh yes most women who are employed are not full-time equivalents for either the standard or Japanese understanding of that phrase." https://www.oecd.org/els/family/LMF_2_1_Usual_working_hours_... )

It is, FWIW, not the case that no one reports overtime. (It is also not the case that everyone reports the correct hours worked. The practice at my previous employer was "We know that you're all diligent and work overtime, and we compensate you for it, of course. The company average is 30 hours of overtime per month. You will, naturally, manage your schedule sufficiently to get your work done in a reasonable fashion, and not violate the Labor Standards Act by working more than X hours per month." And, if you were to check my time cards, you would have seen that I was very diligent about following instructions, in the matter befitting a salaryman at a proper Japanese company.)