Kumai is a Japanese director and screenwriter. He graduated in literature in Matsumoto. He first worked as assistant director to Yutaku Abe and Seiji Hisamatsu and in 1964 directed his first film Teigin jiken: Shikeishű. His other films include Shinobugawa (The Long Darkness, 1972), Sandakan hachibanshokan bohkyo (Brothel 8, 1974), Tempyo no iraka (Ocean to Cross, 1980), Umi to dokuyaku (The Sea and Poison, 1986) that won the Silver Bear and the special jury award in Berlin in 1987, Sen no Rikyu (Death of a Tea Master, 1989) that won the Silver Lion in Venice in 1989, horror Hikarigoke (Luminous Moss, 1992), Fukai kawa (Deep River, 1995), Nippon no kuroi natsu - Enzai (Darkness in the Light, 2001) and Umi wa miteita (The Sea is Watching, 2002) based on the adapted screenplay by Akira Kurosawa.