I did my course a long time ago, my second child was born during the course, zero sympathy fro the company. The Japanese way of doing things is company first, then family. I expect it is still very much the same.
I'd be very careful bringing a family along during the course, especially young kids. The course is long and demanding of your attention throughout. Having the family there can be a distraction which could affect your chances of success. This issue of the course length has been brought up repeatedly but the company will not consider a change.
If you do bring family along, expect ZERO understanding or compromise from the training side of things.
Possibly some of the newer recruits could clarify things now.