After weeks of heated media coverage and speculation over his future, sumo grand champion Harumafuji announced his retirement from the sport Wednesday to take responsibility for the Oct. 25 assault on wrestler Takanoiwa in the city of Tottori.

The 33-year-old top-tier yokozuna from Mongolia submitted a letter of resignation to the Japan Sumo Association earlier in the day through his stablemaster, Isegahama, in Fukuoka.

At the time, senior members of the association were meeting to decide the official ranking of wrestlers for the first tournament of next year.

“Today, I retired because I feel responsible for having injured Takanoiwa,” Harumafuji told a nationally televised news conference from Fukuoka.

The towering wrestler then bowed deeply in apology without raising his head for about 30 seconds.

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“I have done what yokozuna should not have done,” he said. “I told my stablemaster that I want to take the responsibility so that I would not stain the honor of yokozuna.”

Harumafuji will not qualify to become a stablemaster after retirement since he has retained his Mongolian citizenship. Under JSA rules, only a Japanese citizen can obtain the right to become a professional sumo stablemaster.

Harumafuji has reportedly admitted to assaulting Takanoiwa, 27, during a drinking event at a restaurant and bar in the city of Tottori.

The meeting was also attended by other Mongolian wrestlers, including grand champion Hakuho, who reportedly tried to stop Harumafuji during the assault on Takanoiwa, who is also from Mongolia.

Initial reports said Harumafuji struck Takanoiwa on the head with a beer bottle resulting in serious injuries, possibly including a skull fracture.

However, Harumafuji told Tottori police that he struck with his palms, fists and a karaoke machine remote control device, media reports quoted investigative sources as saying.

During the news conference, Harumafuji refrained from detailing exactly what happened during the drinking session. His stablemaster Isegahama said Harumafuji is not supposed to discuss details because of the ongoing investigation into the case.

Instead, Harumafuji just said he “went too ﻿﻿ far” when he tried to “rebuke” Takanoiwa so that he would learn “manners and etiquette.”

“If you strongly believe you are doing a right thing for someone, you can go too far,” he said. “That’s what I learned.”

Media reports have said the sport has a long history of senior sumo wrestlers using violence to bully their juniors in the exclusive atmosphere of a sumo stable.

However, Harumafuji flatly denied that he had ever committed a violent act against other wrestlers or witnessed such incidents, when asked at the news conference.

“I’ve never caused any trouble when I was drinking,” he said. “This incident didn’t happen because of alcohol.”

Harumafuji said he had decided to retire at a much earlier date, but did not make the announcement since the season’s sumo tournament had continued until Sunday.

The scandal came to light after the daily tabloid Sports Nippon reported the assault on Nov. 14.

The incident immediately caused a huge public outcry, having revived dark memories of repeated assaults by senior sumo wrestlers against their juniors.

In 2007, 17-year-old wrestler Tokitaizan, whose real name was Takashi Saito, died during training after being repeatedly beaten by three senior wrestlers.

Stablemaster Tokitsukaze, whose real name was Junichi Yamamoto, was later sentenced to three years imprisonment because he had ordered the assault on Tokitaizan by the three wrestlers, who were also found guilty of related charges.

In 2010, sumo champion Asashoryu, who is also Mongolian, retired from the sumo world following allegations that he had attacked a man outside a Tokyo nightclub.

Media reports over Harumafuji’s scandal have further intensified since stablemaster Takanohana, once one of the most popular sumo wrestlers, formally filed a report on the violent incident with police on Takanoiwa’s behalf. Since then, he has refused to cooperate with the JSA’s investigation, which has perplexed many observers.

Harumafuji made his debut as a professional sumo wrestler in Japan in 2001 and was promoted to the grand champion rank in 2012.

He won 712 matches during his time in the top-level makuuchi division, the sixth highest number of victories. He also won the tournament championship nine times.