Today is a National Holiday in Japan - Kodomo no Hi.
I posted a picture of my friend's Girl's Day display here. This is her Boy's Day display. (She has one daughter and one son).
Another tradition for this holiday is to hang these giant fish flags, called Koinobori. The big black one at the top represents the father, the next one (red) represents the mother, with the other(s) representing the child(ren) in the family.
When I was out walking I saw this little boy hanging a small koinobori next to his family's orange stand.