In terms of raising kids, Japan is a great country to call home.
The insurance and ease of/access to medical care alone is reason to make the move, especially if your husband makes his living as a freelancer.
You then have a tax system (sole proprietor) that works very much to your advantage.
While violent crime is on the rise in Japan, there is no comparison with the US. The majority of the crime in Japan would be consider petty or misdemeanor offenses under US law.
http://www.nationmaster.com/red/country/ja-japan/cri-crime&all=1Some of Japan's biggest problems are sex health and suicide. Both are rooted in a universal lack of communication that plagues the country. But that is a cultural development with which your household won't be burdened if you don't allow it.
In general there is a lack of doctors, nurses, care providers, day care, etc., so the decision about where to live is a very important one.
Also, you may find sports in Japan to be disappointing compared to the US. Baseball, soccer, swimming, golf, tennis, etc. are all available but the expenses are higher than the US and your location could mean your children have very few options.
But overall, art, music, and athletics are very will promoted and balanced throughout the school systems.
Japan doesn't spend as much per capita as some countries, but the overall balance (and lack of cuts) in curriculum is maintained.