A softly spoken, willowy beauty who weeps when she describes her ordeal, Ikumi Yoshimatsu seems an unlikely figure to lead a fight against one of Japan’s most powerful talent agencies. Yet she has become the heroine in a drama that her supporters say has exposed one of the nation’s dirtiest secrets: claims that the Yakuza helps to run the entertainment industry.

Since she became the first Japanese woman to win the Miss International title, Ms Yoshimatsu says she has been blackballed by the industry, stalked and threatened for refusing to join a talent agency. She is now in hiding after filing a criminal complaint against a top executive with the firm. “I am afraid for my life,” she said in a telephone interview.

Last week, Ms Yoshimatsu went public and accused the executive, Genichi Taniguchi, of starting a campaign of intimidation against her shortly after she was crowned Miss International Japan in 2012. She claimed she refused to sign a contract with Mr Taniguchi when an internet search revealed allegations that his company had alleged links to the Yamaguchi-gumi – Japan’s largest crime syndicate. “I told them, morally and ethically I cannot work with such people,” she said.

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In documents and tape recordings submitted to the police, Ms Yoshimatsu claims Mr Taniguchi threatened her and used his industry connections to hound her out of modelling and acting work. At one point, he allegedly burst into a television studio and, she claims, tried to abduct her. Ms Yoshimatsu’s lawyer, Norio Nishikawa, said: “We have recordings proving all this.” He has filed civil and criminal complaints demanding his client be left alone.

Calls to Mr Taniguchi and the talent agency went unanswered, and the police also declined to comment on the case. Mr Taniguchi has denied doing anything to Ms Yoshimatsu. “I’m no stalker,” he told The Japan Times. “I called her father at least twice to try and reach her manager to solve my financial dispute with him. I have no grudge against her.”

Coverage of Ms Yoshimatsu’s claims by the television networks, however, has been strangely muted. Critics claim this is due to the influence of the talent agency and other powerful agencies that keep them supplied with actors and stars. Jake Adelstein, a specialist on Japan’s crime syndicates, said that Ms Yoshimatsu’s fight had embarrassed the industry. “Most of the mainstream media has refused to cover the story because that means no access to talent,” he said.

On Tuesday last week, the scandal deepened at a Tokyo ceremony to hand the Miss International crown to Ms Yoshimatsu’s successor, Bea Rose Santiago of the Philippines. The chair of the current title-holder was empty because, Ms Yoshimatsu claimed, she was barred from attending. She said sponsors and shareholders had been threatened and she was told to “play sick” and stay away. When asked about the situation, a spokesperson for the event organiser, International Culture Association, told the AP news agency it did not want the controversy “to overshadow the event”.

Ms Yoshimatsu’s international-events manager, Matt Taylor, said her refusal to play ball with the industry has cost her $2m (£1.2m) in cancelled contracts. “She is the first woman in this situation to speak out,” he added.

Anti-Yakuza laws introduced two years ago theoretically stop companies from knowingly engaging in business with the gangsters. But analysts say the mob remains strong in the finance and entertainment industries. “Most stars accept it as an unavoidable reality,” Mr Adelstein said.

Ms Yoshimatsu said she had little faith in the police, and hopes that her very public campaign will force the authorities to act. “I want to change the law to protect the victims,” she said. “I will not keep silent and I will not appease my tormentor.”