In Japan, around May 5th (Children's Day) these stylized carp streamers are all hanging around, blowing in the wind. It's the boy's part of Children's Day. The carp represents a strong male, like the fish I guess.
Koinori ra存儲的米飯
boy、carp、children's day、culture、festival、fish、flags、Japan、streamers、こどもの日、鯉幟
男孩、鯉魚、孩子們的一天、文化、節、魚、旗、日本、飄帶、兒童節、鯉幟
資料來源：openclipart ( https://openclipart.org/ )