Masao Kato Honorary Oza (加藤 正夫, Katō Masao, March 15, 1947 – December 30, 2004), also known as Kato Kensei (加藤剱正 Katō Kensei), was a Japanese professional go player. A late bloomer, Kato won 46 titles, including the Oza eight times in a row. He also became the second player to reach 1,200 career wins, behind Rin Kaiho. Kato is the author of The Chinese Opening: The Sure-Win Strategy (published in English by ) and Kato's Attack and Kill (published by Ishi Press).