| Kanji: | 加藤正夫 |
| Nickname: | The Killer |
| Birth Date: | 15 March 1947 |
| Birth Place: | Asakura, Fukuoka, Japan |
| Teacher: | Minoru Kitani |
| Pupil: | Yukari Yoshihara |
| Rank: | 9 dan |
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,[1] Kato won 46 titles, including the Oza eight times in a row.[2] He also became the second player to reach 1,200 career wins, behind Rin Kaiho.[3]
Kato is the author of The Chinese Opening: The Sure-Win Strategy (published in English by Kiseido Publishing Company) and Kato's Attack and Kill (published by Ishi Press).
Kato joined Kitani Minoru's go dojo in 1959, quickly becoming friends with Ishida Yoshio. The two became sparring partners and kept a close relationship up until Kato's death. In 1964, Kato passed the pro exam at age seventeen. Along with Takemiya Masaki and Ishida, the trio became known as the three crows of the Kitani dojo. Kato began qualifying for tournaments early on in his professional career. He made the Honinbo league in 1968 as a 4 dan, a feat unheard of at the time. Kato was unable to progress past the group stages and was relegated. However, he challenged title holder Rin Kaiho the following year, losing four games to two.[4]
He was known as the "Killer" for his attacking style. During a Honinbo league match in 1970, Kato forced 22nd Honinbo Takagawa Kaku to resign after 93 moves.[5] For the early part of his career, Kato was known as the eternal runner-up. He finished runner-up eight times before winning his first titles, the Gosei and Judan, in 1976. Kato went on to win 46 total titles, fourth most in Japan behind Cho Chikun, Sakata Eio and Kobayashi Koichi. At one point, Kato held four of the top 7 titles: Meijin, Oza, Judan and Gosei.
Kato was elected president of the Nihon Ki-in and International Go Federation in early 2004. Under his lead, he eliminated the Oteai, instead introducing new rules to help deal with rank inflation that had occurred over the years. He also increased komi from 5.5 points to 6.5 points and shortened thinking time. Later in the year, Kato fell ill and was hospitalized. He underwent a successful operation on 10 December, but his condition worsened a few weeks later. Kato died on 30 December 2004.[6]
Ranks #5 in total number of titles in Japan.
| Domestic | ||
|---|---|---|
| Title | Wins | Runners-up |
| 4 (1978, 1988, 1991, 1993) | ||
| 2 (1986, 1987) | 2 (1981, 1988) | |
| 4 (1977–1979, 2002) | 5 (1969, 1980, 1995, 1997, 2003) | |
| 4 (1978–1981) | 2 (1982, 1991) | |
| 11 (1979, 1980, 1982–1989, 1993) | 3 (1981, 1990, 1994) | |
| 7 (1976–1979, 1983, 1987, 1997) | 4 (1980, 1984, 1988, 1998) | |
| 3 (1976, 1977, 1987) | 4 (1978, 1981, 1984, 1988) | |
| 3 (1995, 1996, 2003) | 1 (1997) | |
| 2 (1998, 2001) | ||
| 1 (1988) | 3 (1974, 1993, 1994) | |
| 3 (1990, 1991, 1996) | 3 (1992, 1999, 2000) | |
| 1 (1974) | ||
| 4 (1980, 1986, 1995, 1996) | 4 (1993, 1997–1999) | |
| 2 (1988, 1994) | 5 (1980, 1984, 1989, 1998, 1999) | |
| 2 (1970, 1975) | ||
| 1 (1975) | ||
| 1 (1973) | ||
| 1 (1971) | ||
| Total | 46 | 46 |
| Continental | ||
| 1 (2003) | ||
| Total | 0 | 1 |