Harumafuji Kōhei (日馬富士 公平, born April 14, 1984, as Davaanyamyn Byambadorj, Mongolian: Даваанямын Бямбадорж), previously known as Ama Kōhei, is a retired sumo wrestler. He received his promotion to yokozuna, sumo's highest rank, on September 26, 2012. He is the third Mongolian and fifth overall non-Japanese wrestler to attain yokozuna status.
He began his professional career in 2001 and reached the top makuuchi division in 2004. He has won ten special prizes for his achievements in tournaments. In November 2008 he became the seventh foreign-born wrestler in sumo history to reach the second-highest rank of ōzeki. In May 2009, he won his first championship, winning the natsu basho (summer tournament). He has won a total of nine top division championships, three of them with a perfect record.
At 133 kg (293 lb), Harumafuji was the lightest man in the top division as of September 2015. He is noted for his technical skill.
Harumafuji admitted to assaulting fellow Mongolian wrestler Takanoiwa during a regional sumo tour in late October 2017. He withdrew from the November 2017 basho shortly after the allegations surfaced. On November 29, 2017, his stablemaster, Isegahama, submitted Harumafuji's letter of resignation to the Japan Sumo Association.