Mahlyanov's professional sumo debut was in November 2002, starting in the lowest-ranked "jonokuchi" division. He was given the "shikona" of Kotoōshū, derived from his place of origin — "koto", shared by all wrestlers at his stable, and "ōshū", meaning Europe. (Following the September 2006 tournament, he changed one of the characters in his ring name, 州 becoming 洲, although the pronunciation, "shū", is the same for both.) He posted "kachikoshi" (winning records in tournaments) throughout his early career, going 71–15 in the five divisions below the "makuuchi" top division. He reached "makuuchi" in September 2004, only 11 tournaments after his professional debut, the fastest rise since the introduction of the six tournaments per year system in 1958.