Photo story on Koinobori. Koinobori are fish shaped flags which traditionally flown in-front of house in Japan to celebrate Children’s Day ( Kodomo no Hi) on 5th May every year. The flags are used to encourages children to move forward with win as the carp can swim upstream. The flags are made by colorful decorated paper, cloth, nonwoven fabric etc .The sizes of ‘koi flags’ generally one feet to a few meters long.