All around Japan, flying fish can be seen swimming in the air from as early as March, but usually the middle of April, to the middle of May. These windsocks in the images of carp are known as koi nobori, and are part of a spring festival associated with the national holiday, Children's Day, also known as Boy's day (Girls have their own day on March 3, though its not a holiday). The koi nobori are flown from houses, especially those with young boys, as well as throughout the town.

Perhaps the largest koi nobori festival is in Tatebayashi, Gunma, where over 50,000 of the koi nobori stream throughout the town and blanket the lake in the main park, as can be seen in the photo above. The sign to the right claims the festival is the largest in the world.