TOKYO — Sumo veteran Kaio said Tuesday that harsh treatment of wrestlers in training is an integral part of Japan's ancient sport and is partially responsible for his own success.

Japan's ancient sport has been rocked by several recent scandals including one in which a trainer was sentenced to six years in prison for his role in the fatal beating of a young wrestler during training.

Junichi Yamamoto, who went by the name Tokitsukaze when he was master of a sumo stable where wrestlers train and live — ordered three wrestlers, in the name of practice, to beat 17-year-old Tokitaizan, hitting him with beer bottles, a baseball bat and hosing him with cold water.

Tokitaizan, whose real name was Takashi Saito, collapsed after practice and died in June 2007. An autopsy showed bruises and injuries that prosecutors said showed his ordeal was not training.

The incident stunned Japan, tarnishing the image of the traditional sport at a time when it is losing appeal among younger Japanese.

Kaio called the sentencing "reasonable" but said that hazing, in acceptable quantities, is a part of the sport.

"Practice is always tough," Kaio said Tuesday at the Foreign Correspondents' Club of Japan. "I was slapped around as well, partly because the stable master wanted to make me stronger and because of training like that I became stronger."

Kaio has been in sumo's elite division since 1993, longer than any active wrestler. He was promoted to the second highest rank of ozeki in 2000.

Sumo hasn't had a Japanese grand champion since Takanohana retired in January 2003. Since then, the sport has been dominated by Mongolian grand champions Hakuho and Asashoryu, leading many to feel Japan is losing a grip of its own national sport.

Kaio is one of a handful of wrestlers at the rank of ozeki, but at 36 his chances for promotion to the top have come and gone.

"I had my opportunities to be promoted but was unable to withstand the pressure," Kaio said. "There were various circumstances that prevented me from doing the necessary training and I accept the responsibility for that. It's all my fault."

Harumafuji, another Mongolian, won last month's Summer Grand Sumo Tournament and is seen by many as the most likely candidate to be the next grand champion.

Kaio said Mongolians are hungrier and train harder and that's why they are dominating sumo.

"When they are small they are doing Mongolian sumo and other sports," Kaio said. "They are practicing harder than Japanese or anyone else and that's why they are stronger than anyone else."

Kaio has had success over the years. He has won the Emperor's Cup five times and has taken home 10 Outstanding Performance prizes and five Fighting Spirit awards.

While he may not be in line for promotion to grand champion, Kaio says he hopes to add a few more titles to his resume.

"I'm still motivated to win the title," Kaio said. "I haven't thought about retirement but when the time comes I'll be mentally prepared for it."