also: さつきのぼり
Boys' Festival carp streamers
Refers specifically to the paper or cloth carp-shaped streamers (koinobori) flown during the Boys' Festival (Tango no Sekku, now Children's Day) on May 5th. The term is somewhat traditional and may be encountered in historical or seasonal contexts.
Many households put up Boys' Festival carp streamers for Tango no Sekku.
My grandfather carefully stores old Boys' Festival carp streamers.