"Traditionally, salarymen (and they are, by the way, mostly men) are hired into a particular company late in university and stay at that company or its affiliates until they retire."
"The employee hereby promises the company: Your first obligation, in all things, will be to your company. You will work incredibly hard (90+ hour weeks barely even occasion comment) on their behalf."
"Salarymen work large amounts of overtime, although much of it is for appearance’s sake rather than because it actually accomplishes more productive work. Depending on one’s company, this overtime may be compensated or “service overtime” — “service” in Japanese means “thrown in for free in the hopes of gaining one’s further custom”, so your favorite restaurant might throw in a “service” desert once in a while or you might do 8 hours of “service” overtime six nights a week for 15 years."
The whole post is a great read that comes from a first-hand experience.