Sorry about the shortage of info:
There are apparently 40 episodes, I have the 28 first ones (missing ep 22).
The only thing I could find on the internet (not a google specialist) is http://www.nhk.or.jp/lesson/

But this show is from the 80's or something so I'm guessing it is like the first season.

Any info you can find would be great, I will try and more episodes.