I would like my children to learn Japanese. I try to teach a little bit but I'm not fluent myself. I think the best way for them to learn is to immerse yourself in Japan and hear it all the time and use it. I see lots of programs for junior high, high school and college but not one for elementary school. I would like my children to go to a Japanese school for a month or so. In 2 years they would be in elementary school, Kindergarten and preschool. I want them to go to a Japanese school but it would be nice if the teachers speak in Japanese most of the time but are able to speak in English just in case my daughters had questions. I would be willing to help out in the classrooms as well. If anyone knows of a program that would have a school for all those level and it would also be nice if they had an adults class too. I know you cant be fluent in a month but I would like to go back every three years to retain the Japanese that they learn and to understand more of their culture.
Ok maybe I didnt make myself clearn when I explained this. I will be with my children!!! I am not sending them away. I will be renting an apartment and going to school with them. I speak pretty good Japanese but not at fluency.

Why on earth would you send your Kindergarteners to a foreign country! There is a reason why there are not programs for elementary school children they are supposed to be home with their families!

Exchange students generally go at age 15 (14 in some rare cases).

I have never heard of an exchange program for small children, but if you come to live in Japan for a few months/years, which includes one parent working in japan so you may have the right visas, your children will be able to go to public school. But, the teachers do not speak english.
I can guarantee you that sending your children to japanese school for a few months at such a young age will not be much use, they will soon forget what they have learned once they are back in your country, also remember that Japanese kindergarten, elementary age are only starting to learn "Japanese" themselves, so your children may not be receiving the curriculum you would be hoping for.
junior-high/high-schol will be much more profitable.
If you wish so much to have your children learn Japanese from a young age, enrolling them in a Japanese school or international school which has japanese in your country, or take them to a japanese language class, such as some offered by the YMCA. You could take classes yourself too and use a lot of Japanese at home. Or maybe be a host family for japanese exchange students and offer them to baby sit in Japanese as a part-time job.
I think there are many options to teach your children japanese. good luck.