Tokyo: Mongolian sumo wrestler Harumafuji, considered one of the best fighters in the sport, has decided to retire after admitting he attacked a lower-ranking fighter under the influence of alcohol, his teacher said on Wednesday.

The teacher submitted Harumafuji's resignation to the Japan Sumo Association and said the Mongolian fighter had caused trouble for the association and the public, the Japanese media reported. The incident has sparked a huge scandal across Japan where the wrestlers are seen as idols from whom exemplary behaviour is expected.

The 33-year-old wrestler admitted he attacked his compatriot Takanoiwa, 27, with fists and then with the remote control of a karaoke machine in Tottori in east Japan at the end of October. The assault left Takanoiwa with a concussion and a skull fracture forcing him to stay in hospital for four days and preventing his participation in the Kyushu Grand Sumo Tournament which ended on Sunday.

According to witnesses at the bar, Harumafuji may have beaten Takanoiwa for not paying attention and using his mobile phone. Harumafuji, 33, debuted in 2001 and has since won nine championships. In 2012, he was recognized as 'yokozuna' and became the fifth non-Japanese fighter to receive the title.