is a Japanese professional sumo wrestler or rikishi from Elhovo, Bulgaria. He made his professional debut in 2009, reaching the top division two years later, debuting in the November 2011 tournament. Aoiyama has won four Fighting Spirit awards, one Technique award and one kinboshi for defeating a yokozuna. He has twice been runner-up in a tournament. His highest rank has been sekiwake. Aoiyama is one of the heaviest competitors in sumo, weighing around 200 kg for most tournaments. In March 2022, he obtained Japanese citizenship. Early life and sumo background After wrestling for ten years and doing amateur sumo for three, he entered the professional sumo world at the introduction of fellow countryman, ōzeki Kotoōshū, becoming only the second Bulgarian rikishi. He joined Tagonoura stable, run by former maegashira Kushimaumi. When asked by his coach whether he preferred mountains or rivers, he chose mountains and so was given the shikona of Aoiyama, meaning "blue mountain". Career Early career In his professional debut as Aoiyama Kiyohito in the September 2009 tournament, he won the jonokuchi championship with a perfect 7–0 record. He subsequently changed his name to Aoiyama Kōsuke for his jonidan debut in the following November tournament, which he also won with a 7–0 record followed by a playoff win against the sole Kazakhstani wrestler Kazafuzan. In the following January 2010 tournament at sandanme he finally lost his first bout, having won all of his previous 16 matches. This would be his only loss though, and his 6–1 record was enough to propel him into the makushita division in the following March tournament. He again posted a perfect record and took the makushita championship. His meteoric rise would slow starting with his next tournament however. He only managed two wins in his next makushita tournament. This was his first losing tournament. In contrast to his previous successes, he struggled somewhat for several more tournaments at this level. He eventually had enough winning tournaments in upper makushita to allow his promotion into the professional jūryō ranks for the July 2011 tournament. He was promoted to the high rank of jūryō 4 due to the high number of vacancies left by wrestlers forced to retire due to involvement in match-fixing. At this high level he only managed a 7–8 record and moved down two ranks to jūryō 6 for the following September tournament. Suffering from a herniated disc, he was forced to