His younger brother is the anime pioneer Osamu Dezaki.
After graduating from high school, Dezaki took a course in the department of literature at Hosei University.
While at Hosei University, Dezaki took a job at the Toshiba corporation for a period of seven years; during that time he acted as the coach for the company's nine-member volleyball team.
In 1977, he founded the Magic Bus studio, an animation production company.