A Koinobori is carp-shaped streamer which is made of cloth and hung on a rope to catch the wind. It is the symbol of strength and hope and displayed in Japan to celebrate boys in a family. The fifth day of May is Boys' Day and the people display Koinoboris to make wishes for happiness of the boys.
I found this couple of Koinobori-shaped porcelain at a shop in Takamatsu City, Kagawa prefecture, during a business trip. - MT