Jun Kasai (葛西 純, Kasai Jun) (born September 9, 1974) is a Japanese professional wrestler, primarily competing for Pro Wrestling Freedoms. Dubbed the Crazy Monkey (クレイジーモンキー, Kureijī Monkī) for his violent and often self-harmful style of hardcore wrestling, Kasai is considered a breakthrough talent in Japanese wrestling, able to work both hardcore and technical styles. Outside Freedoms, Kasai has worked for the original Pro Wrestling Zero-One, Hustle, Ice Ribbon, Combat Zone Wrestling (CZW) and Big Japan Pro Wrestling (BJW).