The Osaka Sister Killer – Yukio Yamaji

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8th May 2020  •  4 min read

Yukio Yamaji was just 16-years-old when he beat his mother to death with a baseball bat. Due to his young age, he was released from juvenile detention school after just 3 years. The courts would soon discover that this was a grave mistake.

The Osaka Sister Killer - Yukio Yamaji

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Yukio Yamaji was just 16-years-old when he beat his mother to death with an aluminium baseball bat in the apartment they shared in Yamaguchi, Japan. He turned himself in to the police and was transferred to the family court. When asked why he killed his mother, he simply stated: “She did not tell me what she would use her borrowed money for” and: “She complained about my father.”

Based on the circumstances of Yamaji’s life, including the death of his father and the fact that they had struggled financially, the court decided that it would be “possible to reform him,” so he was sentenced to the juvenile detention school in Okayama. Here, Yamaji gained a number of qualifications, including those for welding and hazardous materials engineering. He also underwent a number of psychological tests which indicated that he had a developmental disorder which prevented him from forming lasting relationships.

The Juvenile Law in Japan states that juveniles aged 16 or older are to be sent back to prosecutor’s office in cases where they have committed crimes that result in death. However, this law was only reinforced in April of 2001, six months after Yamaji was sent to the juvenile detention school. Therefore, he served just three years before being released back onto the streets, allegedly a changed man… Shortly before his release, he told his lawyer, Shingo Uchiyama, that he was sorry for killing his mother, adding that “it could not be helped…”

Following Yamaji’s release, he visited his grandmother. She suggested he visit his mother’s grave to which he replied: “I won’t go where my mother is.” He was put on probation and housed in a correction and protection facility in Yamaguchi Prefecture. Then three months after his coming-of-age ceremony, Yamaji vanished.1

The court would soon come to discover that they had made a grave mistake in releasing Yamaji.

On the 17th of November, 2005, a fire was reported at an apartment building in western Osaka prefecture. Once the blaze was extinguished, two bodies were discovered: 27-year-old Asuka Uehara and her 19-year-old sister, Chihiro. They had both been raped and then stabbed in the chest and face with a butcher knife. Suspicion soon fell onto Yamaji, who lived in the same apartment block. When police brought him in for questioning, he readily confessed. “I can’t forget the feelings I felt when I killed my mother and I wanted to see blood,” he said. He told police he left the murder weapon at a shrine several hundred meters away.

Following his arrest, Yamaji was charged with the two murders and the prosecution accused him of committing the murders for nothing more than pleasure. His defence, however, tried to argue that he could not differentiate between right and wrong when he committed the crime and raised the question as to whether he was competent to stand trial. They ordered that Yamaji undergo a psychiatric evaluation as well as other tests to develop a greater understanding of his character as well as his upbringing.

During the opening statements of Yamaji’s first court hearing, the prosecutors said that following his release from juvenile detention school, he moved from place to place and stole money from pachinko parlours. They described how he had moved into the same apartment building as the sisters on the 11th of November, just days before the murders. According to prosecutors, Yamaji had intended on living off the money he stole from the sisters while hiding from the police.2

Yamaji’s defence informed the court that Yamaji had been diagnosed with Asperger Syndrome and suggested that he was unfit to stand trial. The judge, however, accepted other testimony that Yamaji was mentally competent and should stand trial for the murders.

In May of 2006, Yamaji pleaded guilty in the Osaka District Court to the murders of the sisters. Now, it was up to the judge to determine his sentence. According to Yamaji, he speculated that he would be sentenced to death: “Obviously, I will be sentenced to death… I am not afraid of death,” he stated. According to his defence counsel: “He has no desire to live and his feelings do not extent to the life of another person, either. It will probably be impossible for him to sincerely repent from the bottom of his heart.”3

The judge subsequently sentenced Yamaji to die for his crimes. “The defendant is demonically possessed with killing people… The victims were killed amid unimaginable fear and pain, and it is inevitable to hand down capital punishment.”4 According to the judge, one of the reasons behind the sentencing was because Yamaji did not “reflect on his crime.” He suggested that if Yamaji had shown remorse for his actions, he would have received a more lenient sentence.5

In 2009, Yamaji was executed at just 25-years-old. He was hanged alongside two other murderers.

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  1. The Japan News, 25 December, 2005 – “Suspect in Sister’s Murder Thought Reformable After Mom’s Murder”
  2. The Japan News, 2 May, 2006 – “Man Pleads Guilty to Murdering Sisters”
  3. The Japan News, 5 January, 2009 – “Unmasking Capital Punishment”
  4. Kyodo News International, 13 December, 2006 – “Man Sentenced to Death for Killing Sisters”
  5. The Japan Times, 2 May, 2010 – “He’s Unusual, So Why Not Just Kill Him?”


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2 years ago

Why did they even let him go after he killed his mother, should’ve charged him with a life sentence

2 years ago

Just another very sad case of poor justice and a broken / flawed criminal system. Those girls would be alive today if he was properly sentenced for his first crime of murder! He should have been locked up and the keys should have been thrown out! He brutally murdered his own mother in cold blood. It’s mind blowing that they didn’t expect him to do it again.

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