My situation isn't exactly like yours, but I did come with my dependent husband and currently we are expecting
our first baby
We will be having the baby in Japan and I have recontracted for another year, so coming with
dependents is definitely do-able. As Pnk Swtr said, there are lots of people out there with dependents, but usually you won't find them on this forum. A better forum to search might be Gaijin Pot. I'm on there a lot searching for answers to questions all the time. It's been very helpful.
Here is how our experience played out.
I came to Japan as a JET, my husband followed 3 weeks later. It was good to have that time apart, because our apartment needed setting up (we didn't have barely anything because the JETs before us broke their contract and were forced to sell off all their useful goods before they left). On top of that, there were lots of little things I had to do with my work (cell phone application, signing up for bank accounts, internet, amenities bills, etc) so it was nice to have the time and silence to figure those out on my own. It was also nice to culturally adjust so I could help my JET lagged husband get the swing of things when he arrived.
The town we live in is in Kyushu. It's a midsized town. My city seemed to have some sort of agreement with another school to always hire a couple, so our town was equipped with the right sort of apartment to handle us. It had only ever been couples that had lived there. I assume that if you get in, it will be to replace a JET who was either a couple or had kids, but it might be different. My husband didn't find work right away, but eventually (months down the line) he got a great job. Our town was definitely set up for kids. Lots of day cares and schools and classes for housewives to take during the week.
Getting the dependent visa for my husband wasn't too hard (I think, it was a long time ago).
Make sure you bring originals of your marriage license and birth certificates of your kids.
I can't even remember the process that we did anymore, but I know it involved going down to the Immigration office and filling in some paper work and paying a fee. Ask your supervisor, they might have more info. If not, consult Gaijin Pot or do a search on Google. If you are really having issues, get back to me and I will try and dig up our paperwork that we did on the process.
My husband didn't get work right away, but he eventually did (months later). For a dependent to work, you need to file another document with immigration to amend your dependent visa. The dependent visa only allows them to stay in the country, not work...so you have pay some other fee and fill out some other paper to get that done.
Again, not too difficult...just had to make sure we had all the right paperwork with us when we went to the immigration office.
I have been a JET for almost 2 years, and will be going into our 3rd year.
We found out we were pregnant in October, but weren't interested in going home. I checked with my school and they had no problem with me staying on and returning to work after the baby is born (although this is not normal practice in Japan).
Because we have been here 2 years, we have a great community of English and Japanese speaking friends, so there have been many people to help us with doctors appointments and figuring out the child-bearing system here in the country. It has been a great experience so far. Without the language skills though, it can be a run-around and even frustrating. I would try and get connected with your local CIR and explain that you will need a hand with some translation stuff. If they can't help you directly, they might be able to refer you to a Japanese friend or colleague that can. You will probably need all the help you can get for enrolling your kids in school and doctors appointments and all that good stuff. However, you never know...you might end up in a bigger city or a place where English is more readily available. I have heard of English speaking doctors for sure, and my OBGYN knows a lot of English medical terms because I think he studied in Germany. Still, getting the full translation is always better
Anyhow, if you have any other questions, let me know.