Kubo was born inKakogawa, Hyōgo on August 27, 1975.[1] He learned shogi when he was about four years old, and at the encouragement of a friend of his father soon began playing regularly at the Kobe Shogi Center in neighboringKobe. The center was managed by shogi professionalHitoshige Awaji [ja] who became Kubo's shogi teacher after the two played a19-piece "Naked King" handicap game. In 1986, he advanced to the semi-finals of the 11thElementary Student Meijin Tournament [ja] asfifth-grade elementary school student, but lost to the eventual tournament winner and fellow future shogi professionalDaisuke Suzuki. Later that same year, Kubo entered the Japan Shogi Association'sapprentice school at the rank of 6-kyū under the guidance of Awaji. He was awarded professional status and the rank of 4-dan on April 1, 1993, at the age of 17.[2]
Kubo's first appearance in a major title match came in 2000 when he challengedYoshiharu Habu for the26th Kiō title. Kubo advanced to the title match by defeatingMasataka Gōda 2 games to 0 to win thetwo-game challenger playoff, but was unable to defeat Habu, losing the match 3 game to 1.[3] The following year, he also challenged Habu for the49th Ōza title, but lost once again by the same score.[4] In 2007, Kubo once again challenged Habu in the 55th Ōza title match, but was defeated 3 games to 0.[5]
Kubo's first major title victory came in 2009 when he defeatedYasumitsu Satō 3 games to 2 to take the 34th Kiō title.[6] Kubo successfully defended his title for the next two years by defeating Satō once again 3 games to 2 in 2010[7] andAkira Watanabe 3 games to 1 in 2011.[8] Kubo, however, was unable to defend his title for the third consecutive year, losing the 37th title match to Gōda 3 games to 1.[9]
In 2008, Kubo challenged Habu for the57th Ōshō title, but lost the match 4 games to 1.[10] The two met again in 2009 for the 59th Ōshō title, and this time Kubo was the winner by the score of 4 games to 2.[11] The victory made Kubo a "2-crown" (a player who simultaneously holds two major titles) for the first time.[12] Kubo successfully defended his title the following year by defeatingMasayuki Toyoshima 4 games to 2,[13] but lost the 61st Ōshō title match to Satō 4 games to 1 in 2012.[14] Kubo won the title for the third time in 2017 when he defeated Gōda 4 games to 2 to win the 66th Ōshō title,[15] and successfully defend his title in 2018 when defeated Toyoshima once again 4 games to 2 to win the 67th Ōshō title.[16] Kubo, however, was unable to defend his title once again the following year when he lost the 68th Ōshō match to Watanabe 4 games to none.[17]
In September–October 2020, Kubo challengedTakuya Nagase for the 68th Ōza title, but lost the match 3 games to 2.[18]
On November 5, 2021, Kubo defeatedShin'ya Satō in anAsahi Cup Open [ja] to become the 25th person to win 800 official games as a professional and was awarded the "Shogi Honor Fighting-spirit Award" as a result.[19][20]
Kubo is considered to be one of the foremost specialists in theRanging Rook opening and has been nicknamed the "Sabaki Artist" (さばきのアーティスト) by fellow professionals for his skill at handling such positions. He is also known for his ability to persevere in difficult, even disadvantageous, positions and has been nicknamed the "Nebari Artist" (ねばりのアーティスト) as well. Kubo along with fellow ranging rook specialistsTakeshi Fujii andDaisuke Suzuki are collectively referred to as the "Ranging Rook Big Three".[21]
Kubo has appeared in major title matches a total of fifteen times, and has won theKiō title three times andŌshō title four times.[23] In addition to major titles, Kubo has won six other shogi championships during his career.[24]
Kubo has received a number awards and honors throughout his career for his accomplishments both on an off the shogi board. These include awards given out annually by the JSA for performance in official games as well as other awards for achievement.[25][26]
Note: All amounts are given inJapanese yen and include prize money and fees earned from official tournaments and games held from January 1 to December 31.
^"Kubo Shin Ōshō Tanjō! Chōkyūsen o Gyakuten Shi, Kiō to Nikan"久保新王将誕生! 超急戦を逆転し棋王と2冠 [Kubo new Osho is crowned! Comes from behind to win very sharp game to hold two major titles at same time.].Sports Nippon (in Japanese). March 18, 2010. Archived fromthe original on March 25, 2010. RetrievedDecember 19, 2017.羽生善治王将(39)に久保利明棋王(34)が挑戦する第59期王将戦7番勝負の第6局...久保が超急戦を逆転勝利した。初の王将位を奪取して...[Toshiaki Kubo Kioh (age 34), challenger to Yoshiharu Habu Osho (age 39), comes from behind to win a very sharp Game 6 of the 7-game 59th Osho title to win Osho title for the first time.]
^"Kubo Ōshō ga Hatsu Bōei! Azayaka na Sabaki de Shōri"久保王将が初防衛! 鮮やかなさばきで勝利 [Kubo Osho defends title for the first time. Wins with brilliant technique].Sports Nippon (in Japanese). March 16, 2011. Archived fromthe original on August 13, 2014. RetrievedDecember 19, 2017.久保利明王将 (35) が勝ち, 通算成績4勝2敗で初防衛を果たした。[Toshiaki Kubo Ōshō (age 35) wins and defends title for the first time by a score of 4-2]
^"Satō Kudan ga Taitoru Dasshu, Shōgi Ōshōsen"佐藤九段がタイトル奪取 将棋王将戦｣ [Shogi Osho Match: Sato 9-dan captures title].Asahi Shimbun (in Japanese). March 9, 2012. RetrievedDecember 19, 2017.挑戦者の佐藤康光九段(42)が久保利明王将(36)に109手で勝って, 通算成績を4勝1敗とし, タイトルを奪取した。[Challenger Yasumitsu Satō 9-dan (age 42) defeats Toshiaki Kubo Osho (age 36) in 109 moves to win match 4-1 and capture the title.]
