TOKYO — Japan's top boy band agency has issued an apology over sexual assault allegations against its late founder Johnny Kitagawa, with fans demanding Monday that the firm "fully investigate" the matter.

Last month, Japanese-Brazilian singer Kauan Okamoto said he was repeatedly molested by Kitagawa, who established the entertainment empire Johnny and Associates.

Okamoto alleged that Kitagawa, who died of a stroke aged 87 in 2019, assaulted him during his four-year stint with the agency until 2016, starting when he was 15 years old.

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

• Former teen idol alleges sexual abuse by Japan music mogul

Kitagawa was never criminally charged over the accusations.

Julie Fujishima, Kitagawa's niece and the current president of Johnny and Associates, addressed the matter in a video and written statement published Sunday evening.

In the video, she apologized "sincerely" for trouble caused in connection to the allegations, and to the accusers.

"Obviously, we do not believe there was no problem. As a business and as an individual, I absolutely do not tolerate these acts," her written statement said, referring to the documentary and Okamoto's testimony.

"On the other hand, it is not easy for us to simply declare by ourselves whether individual allegations can be recognized as facts or not, when we cannot confirm with the individual directly concerned, Johnny Kitagawa," she wrote.

"This is not the kind of occasion where you can be forgiven by saying 'I did not know'. But the truth is that I did not," added Fujishima, a long-term executive at the agency.

• Japanese entertainment mogul Johnny Kitagawa dies at age 87

A fan group called Penlight said Monday that the company's decision to issue online statements, rather than holding a press conference, had left many questions unanswered.

"We ask for the company to fully investigate and recognize the facts of the matter, to take responsibility as a corporation and apologize to the victims of sexual violence," it said.

Kitagawa launched his talent agency in the 1960s and engineered J-pop mega-groups including SMAP, TOKIO and Arashi.

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

© Agence France-Presse