A sumo grand champion is to retire from the sport after allegations that he assaulted a fellow wrestler, including striking him with the remote control of a karaoke machine.
Mongolian grand champion Harumafuji quit ahead of a probe into his conduct by the Japan Sumo Association (JSA).
Harumafuji's stablemaster Isegahama announced the grand champion's retirement on Wednesday.
He said that Harumafuji "has caused great trouble to the association and the public" and that the grand champion bears responsibility.
Speaking at a packed press conference, the wrestler added: "I have caused much trouble to society.
"I want to apologise to various people in the sumo federation who have supported me. As a grand champion, I have done something that shouldn't be done."
Harumafuji allegedly struck Takanoiwa with his palms, fists and a karaoke machine remote control at a party in late October, fracturing his skull and causing other injuries.
"As a senior wrestler, I felt it was my responsibility to teach him the proper behaviour," Harumafuji said of the encounter in October.
Harumafuji reportedly became aggravated when Takanoiwa repeatedly checked his mobile phone while the two were conversing.
The news has dominated Japanese television talk shows and evening newspapers for weeks as the nation expressed shock at claims against a yokozuna grand champion, whose behaviour in sports and society is expected to be exemplary.
Born Davaanyam Byambadorj, Harumafuji debuted in 2001 and has won the championship nine times, with his most recent victory at the autumn tournament in September.
He was promoted to yokozuna, the sport's highest rank, in 2012.
Harumafuji's retirement is the latest scandal to rock the sumo world.
In 2011, the JSA decided to cancel the Spring Grand Sumo Tournament after revelations that 14 wrestlers were involved with match-fixing.
In 2010, grand champion Asashoryu, also of Mongolia, announced his retirement following reports that he injured a man while intoxicated.