Karoyan Andō (Japanese: 安藤 カロヤン, romanized: Andō Karoyan; born Kaloyan Stefanov Mahlyanov, Bulgarian: Калоян Стефанов Махлянов; born 19 February 1983), known professionally as Kotoōshū Katsunori (Japanese: 琴欧洲 勝紀) and in his coaching career as Naruto Katsunori (Japanese: 鳴戸 勝紀), is a Bulgarian-Japanese former sumo wrestler. He made his debut in 2002, reaching the top division just two years later. In 2005, he was the first European sumo wrestler to reach the rank of ōzeki or 'champion', the second-highest level in the sumo ranking system behind only yokozuna. On May 24, 2008, Kotoōshū made history by becoming the first European sumo wrestler to win an Emperor's Cup. He was one of the longest serving ōzeki in sumo history, holding the rank for 47 consecutive tournaments until November 2013. In January 2014 Kotoōshū obtained Japanese citizenship, a requirement of becoming an elder in the Japan Sumo Association, and he announced his retirement during the following tournament in March. In April 2017 he opened his own training stable, Naruto.
Source: “Kotoōshū Katsunori”, English Wikipedia (CC BY-SA 4.0), excerpt