Jackie! The Japanese in Hawaii also observe Boys Day ... never heard Childrens Day until last few years.
I have two sons so flew two fish ...
Actually they wer/are long windsock type things with elaborate pictures of carp silk-screened on two sides.
I gave the "kites" to my sons when I left ... wish I still had them. Being a windsock they inflated nicely and sort of pulsed and made the carp move (sort of) in a way a kite cannot.

http://my.dmci.net/~dmanchester/Themes/Theme1999/Theme031999-4.htm

Color pictures of windsock type kites :
http://www.mikimaru.net/etshioda/sophia/j-trivia/trivia08.html