TOKYO - An aspiring pop idol, who was stabbed dozens of times by an obsessed fan after she rejected his advances, sued Tokyo police on Wednesday (July 10) for their failure to take steps to protect her despite having made police reports of his death threats.

The savage attack on Ms Mayu Tomita, 23, in 2016 had left her nearly blind in her left eye, and she still has problems breathing and eating, the Asahi Shimbun reported.

She continues to suffer from post-traumatic stress disorder and is unable to leave her house on her own. She told the Asahi in a recent interview: "When I see a person holding a pen, even if it is a friend or my doctor, I become really nervous because I fear I may be stabbed."

Ms Tomita is seeking 76 million yen (S$954,000) in compensation from the Tokyo Metropolitan Government, which has oversight of the Metropolitan Police Department, as well as from her attacker and her management agency, which she said had failed to do enough to protect her.

Tomohiro Iwazaki, now 30, was convicted of attempted murder and jailed for 14½ years in 2017.

The horrific case forced Japan to revise its anti-stalking laws to include social media harassment, and it came after the police apologised in December 2016 for brushing off the threats made on Twitter.

The stabbing occurred just before an idol event in Koganei, western Tokyo, on May 21, 2016. Twelve days earlier, she had told the police of Iwazaki's menacing messages and said she felt her life was in danger.

Iwazaki had sent her nearly 400 tweets, during which his idolatry turned to hatred after Ms Tomita refused to accept the unsolicited gifts he sent her.

Ms Tomita, an undergraduate at the time of the attack, said in court in 2016: "I want him to return the life that I was supposed to live. I want him to return my body without scars."

She added: "He is the kind of person who develops some feelings for someone without asking if they feel the same way, and tries to kill the person if things do not go according to his will. He may come and try to kill me this time."

In her current lawsuit, Ms Tomita said she continues to be bothered by how the police appears to have cast doubt on her version of events, saying they had "no recollection" that she explicitly said she felt her life was in danger.

The Metropolitan Police Department has acknowledged in an internal probe that its officers failed to grasp the gravity of the danger she was in, having assessed that Iwazaki was unlikely to make good on his threats.

Mr Yasuhiro Iwata, the chief of the department's community safety and general affairs division, was quoted by Asahi as saying on Wednesday: "We are making efforts together as one organisation to prevent a recurrence of similar incidents, as we take seriously the fact that we could not prevent her from being attacked although we had been alerted earlier."