This was the example I was thinking of when reading the first part of your message. I'm glad you said it because I feared it would've been seen as an exaggeration if I added it as an example I've heard of.
So to anyone who is reading about this and doesn't trust a single anonymous source, let this second anonymous source add on that I've read about the same behavior, and even more disturbing behavior happening to unmarried female employees (where do you think they source the brides from?).
That said, I've heard about these cases at a few companies. I do not have sufficient evidence to generalize beyond that, only to point out that it does happen (and is tolerated by the legal system, no chance of that in the US), not the rate at which it happens nor if it is a fair generalization of Japanese companies in general.