"Kazuo Koike, who had been hospitalized for a long time, and passed away on April 17th due to pneumonia," the message reads (as translated from Japanese). "Many people love Kazuo Koike and his works, and we thank you very much from our hearts. The funeral was attended only by relatives. Thank you very much for everything."
Koike is best-known for the manga series Lone Wolf & Cub, which he created with manga-ka Goseki Kojima. Becoming known as the Golden Duo, Koike and Kojima went on to create other popular series including Samurai Executioner and Path of the Assassin.
Koike also created several other notable manga, including Crying Freeman (with Ryoichi Ikegami), Lady Snowblood (with Kazuo Kamimura), and Hanappe Bazooka (with Goseki Kojima).
Koike also wrote several Marvel projects, from a Japanese-exclusive Hulk: The Manga in 1970 and even working Marvel itself (with help of C.B. Cebulski) with X-Men Unlimited #50 in 2003.
Koike went on to teach a college course on manga, passing on the skills he learned and was taught to him by Golgo 13's Takao Saito. Students of Koike include Rumiko Takahashi (Ranma 1/2), Hideyuki Kikuchi (Vampire Hunter D), Tetsuo Hara (Fist of the North Star), Yuji Horii (Dragon Quest), and Keisuke Itagaki (Baki the Grappler).
Koike was inducted into the Will Eisner Comic Industry Hall of Fame in 2004.