TOKYO, Japan — A former teen idol said on Wednesday he was sexually assaulted repeatedly by Johnny Kitagawa, the founder of Japan's biggest boyband empire, in a rare public allegation against the late mogul.

The talent agency Johnny and Associates was established by Kitagawa and has dominated Japan's showbiz industry for decades.

Kitagawa died of a stroke aged 87 in 2019, having engineered the birth of J-pop mega-groups including SMAP, TOKIO and Arashi, who amassed adoring fans across Asia.

His young recruits were known collectively as "Johnny's Jrs", and flocked to Kitagawa in the hopes of making it big in the lucrative J-pop industry.

Japanese-Brazilian singer Kauan Okamoto told a news conference he was molested by Kitagawa "15 to 20" times during his four-year stint with the agency until 2016, starting when he was just 15 years old.

He is one of the first people to publicly address Kitagawa's long-alleged history of sexual abuse against young boys, a controversy that resurfaced after a recent BBC documentary.

"I hope other victims will also come forward, all of them," said Okamoto, who believes most of the "100 to 200" young recruits he worked with at the agency were similarly assaulted by Kitagawa.

"I also want the agency's top management, and Johnny himself if he were here today, to acknowledge what took place and make sure such things won't happen again."

Johnny and Associates did not directly address Okamoto's allegations in a statement issued to AFP, but said it was committed to "strengthening corporate governance".

"... we have made it our utmost priority to adapt to the changing environment by establishing transparency" to win "social trust" since Kitagawa's death, the statement said.

Okamoto, now 26, said it was common for Kitagawa's younger talents awaiting a mainstream debut to spend the night at his penthouse apartment equipped with a jacuzzi, bar and a karaoke machine.

He said the first time he was assaulted by Kitagawa, the mogul came into his bed and proceeded to touch his genitals and perform oral sex on him.

He said Kitagawa gave him 10,000 yen (now $75) the following day, without specifying what the money was for.

Allegations of child abuse and sexual exploitation have surrounded Kitagawa for years, but accusers have mostly remained anonymous.

The Shukan Bunshun weekly magazine published a series in 1999 based on accusations made by several boys managed by the entrepreneur.

Kitagawa was awarded damages for defamation following the reports but the verdict was partially overturned on appeal, with the court ruling the magazine had sufficient reason to publish the allegations, according to Kyodo News.

Kitagawa was never criminally charged.

Okamoto said he had no plans to ask police for a posthumous investigation of Kitagawa.

"Thanks to Johnny, my life did change," he said.

"But I also believe what Johnny did -- performing sex acts on me when I was 15 -- and to the other juniors, was a bad thing."

The singer said there was a "general awareness" among the boys under Kitagawa's management that rejecting his advances would hurt their chances of success, though the mogul never explicitly said so.

Kitagawa's words carried such decision-making power that "some juniors even said, 'you have to be at his place to succeed'," Okamoto said.

© Agence France-Presse