The harisen is a giant paper fan, usually made in a closed fashion. It is most traditionally used as part of a manzai act, in which the straight man smacks the funny man in response to their jokes or
Keiichi Yamamoto of Gokuraku Tombo being hit with a harisen
Manzai is a traditional style of comedy in Japanese culture comparable to double act comedy.
Harisen
…The harisen (ハリセン/張り扇, meaning "slapping fan") is a giant paper fan, usually made in a closed fashion. It is most traditionally used as part of a manzai act, in which the straight man (tsukkomi) smacks the funny man (boke) in response to their jokes or idiocy. The Japanese version of the video game…
A pair of manzai performers at a New Year celebration; the tsukkomi at front, the boke behind him (artist unknown, 19th-century Japanese painting)
Print depicting two manzai comedic actors, also in a New Year setting; c. 1825
Yokoyama Entatsu and Hanabishi Achako established the talk show-centered manzai style. They were active since 1919.
All Hanshin-Kyojin, active since 1975.