, previously known as , is a Mongolian former professional sumo wrestler. He was the sport's 70th yokozuna from 2012 to 2017, making him the third Mongolian and fifth overall non-Japanese wrestler to attain sumo's highest rank.

Harumafuji began his professional career in 2001 and reached the top makuuchi division in 2004. He 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 tournament championship. He went on to win a total of nine top division championships, three of them with a perfect record. At , Harumafuji was the lightest man in the top division as of September 2015. He is noted for his technical skill and his rivalry with fellow Mongolian yokozuna Hakuhō.

Harumafuji admitted to assaulting fellow Mongolian wrestler Takanoiwa during a regional sumo tour in late October 2017. He withdrew from the November 2017 honbasho shortly after the allegations surfaced. On November 29, 2017, his stablemaster, Isegahama, submitted Harumafuji's letter of resignation to the Japan Sumo Association.

Early life and sumo background Byambadorj is a native of Ulaanbaatar, Mongolia. His father was a Mongolian wrestler, holding a rank roughly equivalent to sumo's sekiwake. Byambadorj appeared at the Naadam, a Mongolian games festival that includes wrestling, at the age of 15. He was scouted by former yokozuna Asahifuji in July 2000 and subsequently joined Ajigawa stable (now Isegahama stable).

Career He took the shikona or ring name Ama Kōhei and made his first appearance in January 2001. He reached the top makuuchi division in November 2004, rising slowly to komusubi in May 2006. However, a disappointing 4–11 result in this tournament sent him back to the maegashira ranks.

On the eve of the January 2007 tournament, Ama's father was killed in a traffic accident. Nevertheless, he turned in a strong 10–5 record there and earned promotion back to komusubi for March. In May 2007, he made his debut at sekiwake, becoming the ninth foreign-born rikishi to do so. He held his rank with an 8–7 record.

In September 2007, under the komusubi rank, Ama defeated new yokozuna Hakuhō on the opening day and also beat two ōzeki. He also memorably defeated newcomer Gōeidō with a spectacular technique known as okuritsuriotoshi or "rear lifting body slam."this technique is illustrated here . He finished with a 10–5 score and won his first shukun-shō or Outstanding Performance award. He picked up his second in November with another defeat of Hakuhō, and earned promotion back to sekiwake.

In the January 2008 tournament Ama was the only wrestler to defeat Hakuhō, during Hakuhō's successful bid for the tournament championship. This was also his third consecutive defeat of the yokozuna, and this victory helped him to win his third shukun-shō in a row. However, he failed to score more than nine wins, denting his hopes for ōzeki promotion, which normally requires three consecutive double-figure scores. After a poor start to the March 2008 tournament, he had to win his last four matches to barely preserve his rank with an 8–7 record. On the 8th day of the May 2008 tournament, he amazed audiences by defeating Wakanohō with a perfectly executed utchari or spin throw on the bales. After the match, Wakanohō acted violently and was warned. On the 10th day, Ama also threw yokozuna Hakuhō into the seats with an overarm throw, ending his winning streak. After the tournament Ama was awarded his third Technique prize.

Promotion to ōzeki In the July 2008 tournament, he achieved a double-figure score for the first time at sekiwake, and won another Technique prize. In the September 2008 tournament Ama finished with twelve wins, recording his second junyūshō (second-place finish, an informal designation), and was awarded his fourth Outstanding Performance award.

The November 2008 tournament was the most successful yet for Ama, as he won 13 bouts (including his bout against Hakuhō) and his thirty-five victories over the last three tournaments exceeded the thirty three generally required for ōzeki promotion. He reached a play-off against Hakuhō as a result and lost, still, his promotion was now inevitable. He was awarded his fifth Technique prize and achieved another junyūshō. On November 26, 2008, Ama was promoted to ōzeki by the Sumo Association, and on the occasion had his fighting surname changed to Harumafuji. The name was chosen by his stablemaster, Asahifuji.

Ōzeki career

Harumafuji's debut tournament as an ōzeki in January 2009 was inauspicious. Debuting a new name and a new, silver-colored mawashi, he lost his first four matches. On the fifth day he returned to the ring in his customary black mawashi, rallied, and by the end of the tournament secured an 8–7 majority of wins. He did better in the following tournament in March, defeating Asashōryū and winning ten bouts.

In May he went undefeated in his first twelve matches until he was beaten by Hakuhō on Day 13 with a rare leg sweep, susoharai. Harumafuji recovered to defeat Asashōryū the next day with an outer leg trip, sotogake. With Hakuhō falling to Kotoōshū on the same day, both men went into Day 15 with identical 13–1 records. Harumafuji defeated Kotoōshū for a career-best 14–1 record while Hakuhō was victorious over Asashōryū, setting up a playoff. Harumafuji defeated Hakuhō with an under-arm throw, shitatenage, to win his first top division championship. He became the third Mongolian to win the Emperor's Cup, and the eighth foreigner overall. Harumafuji's mother was in the audience to see him awarded the trophy by Japanese Prime Minister Tarō Asō. However, in the following July basho he recorded only a disappointing 9–6.

He pulled out of the November 2010 tournament on Day 4 having injured his right ankle in a defeat to Tochinoshin.

In July 2011, Harumafuji won his second championship, defeating Hakuhō on the 14th day to win his fourteenth straight match and establish a two win lead over his rival. This stopped Hakuhō's streak of consecutive yūshō at seven. It was also Harumafuji's first time since his first yūshō that he had won more than ten bouts in a tournament. Harumafuji commented after his victory, "I really wrestled the sumo of my life. I've had many troubles and injuries since becoming ōzeki but I kept training and got support from a lot of people." He lost his final day match to Kisenosato to finish with 14–1. However, any chance of immediate promotion to yokozuna ended when he scored only 8–7 in the following tournament.

Promotion to yokozuna In the May 2012 tournament, Harumafuji finished with a nearly even record of 8–7. In his final match, he defeated Hakuhō for his 8th win of the tournament, beginning a winning streak. He bounced back in July as he won his third championship without losing a bout, beating Hakuhō on the last day for his first zenshō-yūshō (winning every match in the tournament). Harumafuji got his chance to earn promotion to yokozuna for the third time in his career.

In a September tournament, Harumafuji defeated Hakuhō once again to win his fourth championship and another consecutive zenshō-yūshō. Having won two successive tournaments, Harumafuji met the criteria for promotion to yokozuna. Following this performance, he was formally promoted to be the 70th yokozuna on September 26, 2012. This promotion made him the third consecutive Mongolian-born wrestler, following Asashōryū and Hakuhō, to achieve this rank. He attended a ceremony bestowing him the title, and said "With the awareness of what it means to be a yokozuna, I will devote my body and soul to the way of sumo."

He performed his first yokozuna dohyō-iri (ring-entering ceremony) on September 28, 2012, in front of 3,000 people at the Meiji Shrine in Tokyo, with Aminishiki as the sword carrier and Takarafuji as the dew sweeper. After the two-minute ceremony was over he said "I aimed to carry out a beautiful dohyoiri". His stablemaster had coached him the previous day on how to do the ring-entering ceremony in the Shiranui-style, the style used by himself as an active yokozuna.

Yokozuna career Harumafuji's first tournament as a yokozuna in November 2012 was a disappointing one, as he gave up a kinboshi to Okinoumi on just the second day, and from 9–1 up finished with a 9–6 record. He became the first new yokozuna ever to lose his last five matches. Despite being criticized heavily for his lackluster debut at the rank of yokozuna, Harumafuji bounced back with a tremendous showing in the following tournament winning all 15 matches, for his third zenshō-yūshō. He struggled again in March, giving up kinboshi to Takayasu, Chiyotairyū and Toyonoshima and also losing his last three matches. He did slightly better in the May tournament, scoring 11–4, but was never in contention for the championship. In the November tournament of 2013, he won his second championship as a yokozuna with a 14–1 record, decided by a final-day victory over Hakuhō.

Harumafuji was not able to build on this success as he had to sit out the January 2014 tournament due to injury, and subsequently was not in contention for the championship on the final day of any tournament in 2014. Excluding the March tournament where he won his first 11 matches before losing three in a row, he was not a serious contender at all in any of the tournaments' second weeks, having dropped at least two matches before the midway point in three of them, and withdrawing from the September tournament due to an eye injury during the first week. Thus 2014 was his first year without a championship since 2010.

Harumafuji was a runner-up in January 2015's opening tournament of the year with an 11–4 record, his second runner-up performance as a yokozuna and first since March 2014. He withdrew from the July 2015 tournament in Nagoya on just the second day after injuring his right elbow, and the injury also kept him out of the following tournament in September. This means his title drought had extended to two years by the time he made his comeback at the November 2015 tournament in Kyushu. He was defeated on the second day by Ōsuna-arashi, but won his next twelve bouts, including victories over his fellow yokozuna Hakuhō and Kakuryū, to enter the final day with a one match lead over Hakuhō and the maegashira 10 Shōhōzan. He lost to Kisenosato to end the tournament at 13–2 but claimed the championship when Hakuhō was beaten by Kakuryū in the final match. Harumafuji commented "I wanted to win the championship with a victory but I am happy I could respond to expectations of the fans".