Kazuo is known for being a grandmaster of Japanese horror manga. He started publishing his work while still in high school, and after graduation he began working professionally in the field. His early works included Betsu-Sekai (Another World) and Mori-no-Kyoudai (The Brother and Sister in a Forest), which were published for Kashi-hon magazines that were not sold but rented. It was in 1962, when he moved to Tokyo, that Kazuo developed his signature horror style. His works such as Kuchi ga Mimi made Sake-ru Toki (The Moment The Mouth Tears to Ears), Hebi Shoujo (The Snake Girl) and Hito-kobu Shoujo (A Girl Who Has A Human-faced Lump on Her Cheek) helped establish him as a master in the horror genre.