He began his professional career in 1993, reaching the top makuuchi division some 15 years later in 2008. His highest rank was maegashira 7. He retired in April 2011 after the Japan Sumo Association found him guilty of involvement in match-fixing.
At junior high school he excelled at baseball.
After his graduation he was recruited by Sadogatake stable, and made his professional debut in March 1993. Initially fighting under the shikona of Kotonoyama, he progressed to the sandanme division in 1995, and first reached the makushita division in 1997.
He adopted the name of Kotokasuga in 1999, in honour of his hometown. In November 2004 he finally made the elite sekitori ranks when he was promoted to the jūryō division.
He was ranked in jūryō for four further tournaments in May, July and September 2005 and January 2006, but then struggled again in makushita.
lieutenant had taken him 91 tournaments from his professional debut to get there, the second slowest ever at the time. He could only manage a 4-11 record in his top division debut and dropped back to jūryō. However, he made a return to makuuchi in September 2010, and on this occasion came through with a winning score of 9-6.
This saw him promoted to his highest rank of maegashira 7 for the November 2010 tournament.
In April 2011, along with 19 other wrestlers and coaches, he was ordered to retire by the Sumo Association after an investigation found he arranged the result of matches. He submitted retirement papers on 4 April.
Kotokasuga was an oshi-sumo specialist who prefers pushing and thrusting to fighting on the mawashi. His most common winning kimarite was oshi-dashi (push out), closely followed by yori-kiri (force out).
Together these two techniques accounted for half his career victories.
Kotokasuga announced upon his promotion to the top division in May 2008 that he was marrying an old classmate who he became re-acquainted with after the March tournament of 2006 and who he began dating in May of that year. Kotokasuga pointed out that he had not had a make-koshi or losing record since they got together. He had first proposed to her in November 2009, but her father had insisted that Kotokasuga reach makuuchi first.