Kotomitsuki Keiji (琴光喜 啓司; born April 11, 1976 as Keiji Tamiya (田宮 啓司)) is a Japanese former professional sumo wrestler from Okazaki City. A former amateur champion, he turned professional in 1999. He reached the top makuuchi division in November 2000 and won one yūshō or tournament championship, in September 2001. He was a runner-up in eight other tournaments, and earned thirteen sanshō or special prizes. He is one of six wrestlers in the history of sumo to receive all three sanshō in the same tournament, accomplishing the feat in the November 2000 honbasho. After a record 22 tournaments at sekiwake, he achieved promotion to sumo's second highest rank of ōzeki in July 2007 upon winning 35 out of 45 bouts in three consecutive tournaments. This made him at 31 the oldest man to reach ōzeki in the modern era. He wrestled for Sadogatake stable. On July 4, 2010, he was expelled from professional sumo by the Japan Sumo Association for his involvement in an illegal gambling ring.

Kotomitsuki is a graduate from Tottori Jōhoku High School and had an extremely successful college sumo career, winning a record 27 amateur national titles while at Nihon University. He made his professional debut in March 1999. Because of his achievements as an amateur, he was given makushita tsukedashi status and allowed to leapfrog the lower divisions. Initially fighting under the shikona of Kototamiya, adapted from his own surname, he adopted the name of Kotomitsuki upon reaching the jūryō division in November 1999. He was promoted to the top makuuchi division in May 2000 but missed the entire tournament through injury. On his proper debut three tournaments later, he was runner-up to yokozuna Akebono with an outstanding 13–2 record. He was awarded all three special prizes on offer; a rare achievement. He was immediately promoted to sekiwake.

Kotomitsuki took his only top division yūshō or championship in September 2001, whilst ranked as a maegashira. He won with a 13–2 record in a tournament that saw only one ōzeki and one yokozuna complete all 15 days. He finished in third place with a strong 12–3 score in January 2002 but suffered a broken jaw on the 14th day of the Osaka tournament in March, which required surgery and forced him to miss the following tournament in May. Due to his stablemaster not submitting the paperwork in time, he failed to get public injury status and fell back to the maegashira ranks. He recovered to produce another runner-up performance in September 2002, and was also runner-up in September 2003 and January 2004, each time from a maegashira position.

Kotomitsuki holds the record for most tournaments spent at sekiwake in the modern era. Although he could only manage four wins at his first attempt at sekiwake, he was ranked there for 22 tournaments in total, including eleven in a row from November 2005 to July 2007. For much of that time he was consistent rather than spectacular, posting a succession of 8–7 scores in 2006.

In May 2007 ōzeki Tochiazuma retired, and Hakuhō was promoted to yokozuna. This meant that there were now only three ōzeki rather than five, and Kotomitsuki was once again a strong candidate for promotion. He followed up a 10–5 record in March with a 12–3 score and runner-up honours in May (his first jun-yusho in over two years), with the Sumo Association's chairman Kitanoumi indicating that 12 wins in the following tournament would be enough to clinch ōzeki promotion. In July 2007 Kotomitsuki produced a 13–2 score, defeating west yokozuna Hakuhō and once again finishing runner-up, this time to east yokozuna Asashōryū. He lost to Kisenosato on the final day, missing the chance of a playoff for the championship with Asashōryū and the first yūshō for a Japanese born wrestler since January 2006.

Kotomitsuki's ōzeki promotion, confirmed on 25 July 2007, was of special significance to Kotomitsuki and the Sadogatake-beya. Having missed qualifying in 2002 due to a combination of injuries and bad timing, Kotomitsuki was seen by detractors as having insufficient will and being slightly advanced in age to attain ōzeki status. For comparison, Tochiazuma who reached ōzeki in 2002 is Kotomitsuki's junior by 7 months. At the age of 31 years 3 months, Kotomitsuki proved the naysayers wrong, becoming the oldest wrestler to attain the rank in the modern era.

Kotomitsuki scored a respectable ten wins on his ōzeki debut in September 2007, but at the end of 2007 he underwent surgery to remove gallstones. He was not at his best in the 2008 New Year tournament but won his eighth bout on the final day to achieve a kachi-koshi or winning score. He produced another unremarkable 8–7 mark in March, but did manage to end his 28 consecutive defeats against his nemesis Asashōryū. In July 2008, in his "home" tournament in Nagoya, he finished as runner-up to Hakuhō on 11–4, the eighth and final time in his career he was a tournament runner-up (and his only as an ōzeki). He matched this score in September, although he finished in third place behind Hakuhō and Ama.

Entering the January 2009 tournament with a gout problem in his right ankle, Kotomitsuki took his first make-koshi or losing record as an ōzeki, breaking a run of twenty consecutive kachi-koshi scores. On Day 12 he was forced to pull out of the tournament, leaving him kadoban (in danger of demotion from ōzeki) for the first time. He secured the necessary number of wins in the following tournament in March, which included another victory over Asashōryū. In July 2009 he defeated Hakuhō and finished in third place with a fine 12–3 score – the last time he was to win more than ten bouts in a tournament. He won his first seven matches in September, the best start in his ōzeki career, but then faded in the second week and finished on 9–6. After a mediocre 8–7 in November, he pulled out on the 8th day of the January 2010 tournament with only one win, citing injuries to his left knee and foot. He held his ōzeki rank with a 9–6 score in March.