After completing high school, Dezaki worked at Toshiba while studying literature at Hosei University. At the same time, he pursued his dream of working in movie production. He served as a coach for Toshiba's nine-member volleyball team and began building an anime production team. After seven years with Toshiba, Dezaki left to work for Gisaburou Sugiis company Art Fresh alongside his younger brother Osamu. His early works included writing the script for Attack No.1 and storyboarding Kyojin no Hoshi. In 1969, he became a freelancer, working on scriptwriting, production, and direction for Tokyo Movie Shinsha, Tatsunoko Production, and Sunrise. He founded Magic Bus in 1977 and produced and animated Shin Kyojin no Hoshi. Osamu is an anime director who has worked with his brother.