Grand champion Kisenosato announced his retirement Wednesday, sending shockwaves throughout the sumo world and once again leaving the sport without a Japan-born grand champion.

With tears streaming down his face, the 32-year-old Ibaraki native lamented that he was unable to carry out his duties as one of the sport's elite but said he leaves the ring without any regrets.

"Even though it's very regrettable that I wasn't able to live up to everyone's expectations as a yokozuna, I don't regret one bit of my career on the dohyo," he said.

(Kisenosato attends a press conference at Ryogoku Kokugikan in Tokyo on Jan. 16, 2019, to announce his retirement.)

At age 30, Kisenosato was the 72nd wrestler and most recent one to reach sumo's highest rank, and became the first Japan-born fighter to be promoted to yokozuna since Wakanohana in 1998.

But injuries to his chest, left arm and shoulder plagued Kisenosato throughout his reign atop the rankings, and he only completed two of the 12 grand tournaments held during his time as a yokozuna.

Mongolian grand champions Hakuho and Kakuryu now stand alone at the top of the banzuke, following the retirement of their compatriot Harumafuji over an assault scandal in November 2017.

Kisenosato helped boost sumo's popularity throughout Japan in 2017, when he won back-to-back top division titles despite sustaining chest and left arm injuries in his yokozuna debut at the Spring meet that year.

"I feel like I couldn't have made it here on my own. I was supported by a lot of people and I remember the face of each person. I have nothing but extreme gratitude," Kisenosato said.

His success at the top was short-lived, however, as the nagging injuries forced him to miss part or all of the next eight straight grand tournaments, the most ever by a yokozuna.

(Kisenosato celebrates after winning the Spring Grand Sumo Tournament in March 2017.)

He temporarily fended off talk of his retirement last September when he went the distance at the Autumn meet, finishing the tournament with a 10-5 record as Hakuho collected a record-extending 41st makuuchi division title.

But less than two months after losing four straight bouts at the Kyushu meet, the most consecutive opening losses by a yokozuna in 87 years, Kisenosato suffered his third straight defeat at the New Year Grand Sumo Tournament at Tokyo's Ryogoku Kokugikan on Tuesday, cementing the doubts over his ability that had built up over the past two years.

"I had practiced and gotten in shape before the tournament," Kisenosato said. "I had a feeling inside like 'this is do or die' and I trained well. The result of that came in the form of three losses from opening day, and I don't have a single regret."

Not counting forfeits, it was his eighth straight loss since September, the worst run for a yokozuna since the 15-day grand tournament format began in 1949.

"Since the injury, I was confident that I was doing the best I could. I wrestled with everything I had in the world," he said. "But I felt for the first time that I was unable to go on."

Kisenosato's 36 combined wins since his promotion in March 2017 are nearly 20 less than Mienoumi, who retired in 1980 and had held the lowest win-loss ratio of any yokozuna since the annual six grand tournament format came into effect in 1958.

While the impending retirement had been expected for some time, the news was still shocking given Kisenosato's vibrant start. He made his professional debut in 2002 at the age of 15, and was the second youngest wrestler after Takanohana to be promoted to the juryo division at 17 years and 9 months.

The teenage grappler, known for his brute force and left-hand under, right-hand over-arm grip technique, spent just three tournaments in the second division before making his top flight debut at the end of 2004.

His departure leaves Hakuho and Kakuryu standing at the zenith of a sport reeling in the wake of violence and scandals, while sumo's younger wrestlers are looking to fill in the gaps.

"It's lonely now. I've run out of words to express my appreciation for his efforts," Hakuho said upon learning of his fellow grand champion's retirement.

(From left, Hakuho, Kisenosato and Kakuryu)

The Mongolian powerhouse said his most memorable moment of his Japanese colleague was when Kisenosato defeated him at the 2010 Kyushu tournament, ending Hakuho's record 63-bout win streak.

"I felt like he knocked me down without holding anything back," Hakuho said. "I was happy that a grand champion was the one who ended my win streak, and I've been able to do my best up until now as a result of the loss."

As a rank-and-filer, Kisenosato earned three "kimboshi" prizes for defeating a yokozuna. Before reaching ozeki, he won five Outstanding Performance prizes, three Fighting Spirit prizes and one Technique prize.

Over 101 tournaments, Kisenosato recorded 800 wins and 496 losses, and his 714 wins in the top division are the sixth best in the sport's history.

Kisenosato also announced Wednesday that he will take on coaching duties under the name "Araiso" and train younger wrestlers as a sumo elder.

"Whether or not I'm retiring with my head high, I've always thought about coaching," he said. "But while I've decided to continue on with sumo so I can support others, I'm sorry to have left a result like this."