I work in IT and my wife is Japanese, so getting in and working in Japan wouldn't be much of a problem. The language barrier is an obstacle, but I'm sure I could get my Japanese to an acceptable level. However, we have decided a long time ago to live, work and raise our children in Europe. This for a number of reasons:
The work environment
It's not just the long overtime, but also the mandatory going out with your colleagues after work and the strict hierarchical culture in most companies. Showing initiative, efficiency and flexibility are discouraged and promotions are often not based on merit, but on how long you have been working at a company. Taking (long) holidays is frowned upon. And if you do, expect to spend at least one day shopping for souvenirs for your colleagues.
Basically, in Japan you are expected to show dedication to your company over your family. A very foreign concept for Europeans were family always comes first and companies accommodate that.
Raising children
Daycare is very expensive, if you can find it within a reasonable distance. Companies don't really accommodate you. If you come in late/leave early to drop of or pick up your children, your carriere gets put on hold. It is expected that this is the responsibility of the wife, not the husband. Also the whole education system is not based on acquiring social skills and gain knowledge, but on passing standardized tests. Bullying is a major problem that is often overlooked or ignored.
General quality of life
While Japan has some very good things like culture, quality and availability of amazing food and it's a very safe place to live. It's also had it's fair share of negative things that kind of get to you in the long run.
General unwillingness to mingle with, show emotions to and have deep conversations with outsiders. Contact with most Japanese will be superficial at best.
Housing is tiny, health care is so expensive you have to save up a lot of money just in case you get sick, public transport is crowded and expensive. Also it's a consumer culture. Everybody is always chasing the latest (luxury) product or latest food trend. This gets very tiring after a while.
Now, we still love visiting Japan once a year and we are planning on retiring (part of the year, f*ck summer) there. But this will probably be outside of the major cities.