Karoyan Andō, known professionally as Kotoōshū Katsunori and in his coaching career as Naruto Katsunori, is a Bulgarian-Japanese former sumo wrestler. He made his debut in 2002, reaching the top division just two years later. In 2005, he reached 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.

Sumo is a form of competitive full-contact wrestling where a rikishi (wrestler) attempts to force his opponent out of a circular ring (dohyō) or into touching the ground with any body part other than the soles of his feet.