1. I believe that little children would not understand the main message of this animation unless it is made into a different parable.
2. As said in 1 the body function is made to entertain the children more than telling the meaning of the power plant.
3. Japanese version has a much more soft touch and both Boys and Girls would watch without distinction.
4. Defiantly Genpatsu-kun, nuclear boy has too much characteristics of which a human does, and therefore gives off much more discomfort.