Born in Tokyo, Shimazaki attended Rikkyo University where he studied under Shigehiko Hasumi, made 8mm films, and appeared in the then amateur works of other Rikkyo graduates such as Kiyoshi Kurosawa. After graduating, he worked at the film company Cine Saison and starting writing about film and doing long interviews of directors such as Quentin Tarantino and Takeshi Kitano for magazines. While working as a projectionist for the Athénée Français Cultural Center in Tokyo, he saved up enough money to make his first 35mm film, Okaeri, for which he won the Wolfgang Staudte Award at the Berlin Film Festival in 1995. His next feature film, Not Forgotten, was screened at the Three Continents Film Festival, where its stars, Tomio Aoki, Tatsuya Mihashi, and Minoru Oki, shared the best actor award. Having developed a close relationship with Takeshi Kitano, Shinozaki has made a documentary on the filming of Kikujiro as well as a TV movie based on Kitano's autobiographical novel Asakusa Kid. He has also produced the Cop Festival series featuring short films by directors such as Kiyoshi Kurosawa, Shinji Aoyama, Akihiko Shiota, and Hirokazu Koreeda. Continuing to write on film, he has published a history of horror cinema with Kiyoshi Kurosawa.