Koike was a prolific Japanese manga writer, novelist and entrepreneur.
Early in Koike's career, he studied under Golgo 13 creator Takao Saitou and served as a writer on the series.
Koike, along with artist Goseki Kojima, made the manga Kozure Ookami, and Koike also contributed to the scripts for the 1970s film adaptations of the series, which starred famous Japanese actor Tomisaburo Wakayama. Koike and Kojima became known as the "Golden Duo" because of the success of Kozure Ookami. Another series written by Koike, Crying Freeman, which was illustrated by Ryoichi Ikegami, was adapted into a 1995 live-action film by French director Christophe Gans. Kazuo Koike started the Gekika Sonjuku, a college course meant to teach people how to be mangaka.
In addition to his more violent, action-oriented manga, Koike, an avid golfer, has also written golf manga.
