The Okan (王冠, literally "crown" or "king's crown") is a Go competition conducted by the Japanese Nihon-Kiin. There is a single game played between the title holder and a challenger. Unlike other tournaments which are open to all players, only players in the Nagoya branch of the Nihon-Kiin can compete. The winner's purse is a small 1,700,000 Yen ($15,000).
| Player | Years Held |
|---|---|
| Sakai Toshio | 1950 - 1955 |
| Shimamura Toshihiro | 1957 - 1965, 1974, 1975 |
| Iwata Tatsuaki | 1967, 1969, 1970, 1976, 1979, 1980 |
| Hane Yasumasa | 1972, 1978, 1983, 1992 |
| Yamashiro Hiroshi | 1977, 1981, 1982, 1984 - 1987, 1993 - 1996, 2000, 2001, 2005, 2010 |
| Ogata Masaki | 1988 - 1991 |
| Nakano Hironari | 1997, 1998 |
| Hane Naoki | 1999, 2002-2004, 2007-2009, 2011-2014 |
| Matsuoka Hideki | 2006 |