| Hideyuki Sakai | |
| Fullname: | Hideyuki Sakai |
| Kanji: | 坂井秀至 |
| Birth Date: | 23 April 1973 |
| Birth Place: | Sanda, Hyōgo, Japan |
| Residence: | Osaka, Japan |
| Turnedpro: | 2000 |
| Rank: | 8 dan |
| Affiliation: | Kansai Ki-in |
Before becoming a professional, Sakai was majoring in medical science at Kyoto University. For a long time, Sakai was the strongest amateur player in Japan, and when he won the World Amateur Go Championship in 2000, the Kansai Ki-in awarded him professional 5 dan (after defeating two 5 dan and two 7 dan players). He was also the first player in Japan to be awarded a special 8 dan (amateur) diploma. In 2003, he won the biggest Kansai Ki-in tournament, the Kansai Ki-in Championship. In 2004, he was runner-up for the Shinjin-O title, losing to Mizokami Tomochika two games to one (losing both by half point). He is currently active in various tournament leagues for both the Nihon Ki-in (participation in Meijin league 2005–present) and the Kansai Ki-in.
In 2010, Sakai won the Gosei title, defeating title-holder Cho U 3–2.
| Domestic | |||
|---|---|---|---|
| Title | Wins | Runners-up | |
| 1 (2010) | 1 (2011) | ||
| 1 (2004) | |||
| 4 (2003, 2011–2013) | 3 (2004, 2007, 2014) | ||
| Total | 5 | 5 | |