This character is a Other Symbol and is commonly used, that is, in no specific script.
The glyph is not a composition. Its East Asian Width is wide. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. U+1F38F offers a line break opportunity at its position, except in some numeric contexts.
The CLDR project calls this character “carp streamer” for use in screen reading software. It assigns these additional labels, e.g. for search in emoji pickers: carp, celebration, streamer.
This character is designated as an emoji. It will be rendered as colorful emoji on conforming platforms. To reduce it to a monochrome character, you can combine it with Variation Selector-15: 🎏︎ See the Emojipedia for more details on this character’s emoji properties.
The Wikipedia has the following information about this codepoint:
Koinobori (鯉のぼり), meaning 'carp streamer' in Japanese, are carp-shaped windsocks traditionally flown in Japan to celebrate Tango no sekku (端午の節句), a traditional calendrical event which is now designated as Children's Day (子供の日, Kodomo no hi), a national holiday in Japan. Koinobori are made by drawing carp patterns on paper, cloth, or other nonwoven fabric. They are then allowed to flutter in the wind. They are also known as satsuki-nobori (皐のぼり).
Children's Day takes place on May 5, the last day of Golden Week, the largest break for workers and also a week in which many businesses, state schools, and some private schools close for up to 9–10 days for the designated national holidays. Landscapes across Japan are decorated with koinobori from April to early May, in honor of children for a good future and in the hope that they will grow up healthy and strong.
The koinobori is included in Unicode as U+1F38F🎏CARP STREAMER.