Kids That Kill

Yukio Yamaji | Osaka Sister Killer | Juvenile Matricide to Double Murder

Yukio Yamaji was 16 when he bludgeoned his mother to death in Yamaguchi (2000), was paroled three years later, and in 2005 raped and murdered two Osaka sisters – crimes that led to a death sentence and execution by hanging.

Yukio Yamaji photo
Yukio Yamaji

Yukio Yamaji | Osaka Sister Killer

Japanese Serial Killer

Last updated: November 17, 2025

Yukio Yamaji |

Juvenile Matricide to Double Murder

  • Full name: Yukio Yamaji
  • Born / Died: Aug 21, 1983 – July 28, 2009 (age 25)
  • Also known as: “Osaka Sister Killer”
  • Primary offenses: Matricide (2000); rape – double murder of sisters (2005)
  • Locations: Yamaguchi (matricide); Naniwa Ward, Osaka (double homicide)
  • Arrested: Dec 5, 2005 (for the Osaka case)
  • Conviction & sentence: Murder (3 counts); death (Osaka District Court, Dec 13, 2006)
  • Status: Executed by hanging at Osaka Detention House, July 28, 2009 (with Hiroshi Maeue; third man executed in Tokyo)

Classification & Characteristics | Yukio Yamaji

Yamaji is classified as a violent recidivist who first killed as a juvenile (parricide) and escalated to sexual homicide as an adult. The Osaka murders targeted strangers, showing opportunistic predation, post-offense arson, and a stated attraction to the “feeling” of killing – markers consistent with hedonistic/anger elements.

Psychologically, records emphasize early destabilization (father’s death, financial strain), a first lethal act at 16, brief juvenile incarceration, and rapid relapse within two years of parole. His own statements – “I couldn’t forget the feeling when I killed my mother” – underscore intrinsic violent reinforcement rather than instrumental motive.

Timeline of the Yukio Yamaji Case →

  • Jul 29, 2000: At 16, kills his 50-year-old mother in Yamaguchi; arrested July 31.
  • Oct 2003: Paroled from juvenile reformatory.
  • Nov 17, 2005: Rapes and murders Asuka Uehara (27) and Chihiro Uehara (19) in Naniwa Ward, sets fire to their apartment.
  • Dec 5, 2005: Arrested; gives statements referencing prior killing.
  • Dec 13, 2006: Death sentence (Osaka District Court).
  • Jun 2007: Appeal withdrawn; death sentence finalized.
  • Jul 28, 2009: Executed (Osaka Detention House), alongside Hiroshi Maeue; a third execution in Tokyo same day.

Case Summary | Yukio Yamaji

Yamaji’s path moved from a juvenile parricide (2000) to an adult double murder (2005) after parole. In Osaka, he attacked two sisters—Asuka and Chihiro Uehara—in their apartment, raped the elder, murdered both, then set the scene ablaze. Arrested weeks later, he confessed, citing an inability to forget the feeling of his first killing. The Osaka District Court imposed death in 2006; after withdrawing his appeal in 2007, he was hanged in 2009.

→ Quick Answers

  • Where did it happen? Naniwa Ward, Osaka, Japan (double murder); Yamaguchi (matricide).
  • Victims’ names (Osaka)? Asuka Uehara (27) and Chihiro Uehara (19).
  • Arson involved? Yes—apartment set on fire post-offense.
  • Sentence & court? Death, Osaka District Court (Dec 13, 2006).
  • Appeal? Filed, then withdrawn (2007), finalizing sentence.
  • Current status? Executed by hanging, July 28, 2009 (Osaka Detention House).

🕊️ Victims of Yukio Yamaji

  • His mother (50) – Yamaguchi, July 29, 2000. Name not widely reported in English-language sources.
  • Asuka Uehara (27) – Naniwa, Osaka, Nov 17, 2005.
  • Chihiro Uehara (19) – Naniwa, Osaka, Nov 17, 2005.

→ FAQs

How old was Yamaji at his first killing?

16 (matricide, 2000).

Did he know the Osaka victims?

No – stranger-targeted; the sisters had not met him before.

What ended his legal process?

He withdrew his appeal; sentence finalized; executed in 2009.

Yukio Yamaji | Osaka Sister Killer

Yukio Yamaji | Osaka Sister Killer

The Story

Juvenile Matricide to Double Murder

A First Killing at Sixteen (2000)

In Yamaguchi, a 16-year-old Yamaji killed his mother with a metal bat. He called police and was arrested two days later. After juvenile disposition, he was paroled in 2003.

Parole and a Return to Violence (2005)

Two years post-parole, he targeted an Osaka apartment occupied by sisters Asuka and Chihiro Uehara. The sexual assault and double murder were followed by arson to destroy evidence.

Arrest and Statements

Arrested on Dec 5, 2005, he reportedly told police he “couldn’t forget the feeling” from the first killing and “wanted to see blood,” reflecting internal reinforcement rather than a practical motive.

Trial, Waived Leniency and Death Sentence

The Osaka District Court imposed death on Dec 13, 2006. Though an appeal was initiated, Yamaji withdrew it in 2007, finalizing his sentence.

Execution in Osaka (2009)

On July 28, 2009, Japan executed three inmates: Hiroshi Maeue and Yukio Yamaji in Osaka, and Chen Detong in Tokyo – a day that drew rights-group criticism over secrecy and lack of notice.

Legal Status | Paper Trail | Yukio Yamaji

  • Charging & Venue: Osaka District Court – double murder, arson (2005 case).
  • Judgment: Death sentence on Dec 13, 2006 (Osaka District Court).
  • Appeal posture: Appeal withdrawn (finalized June 2007).
  • Execution: July 28, 2009, Osaka Detention House (with Hiroshi Maeue; third execution same day in Tokyo).
  • Context & secrecy: Rights groups (Amnesty) criticized lack of notification and transparency in Japan’s executions.

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👉 This page is part of the WickedWe True Crime Archive – a resource for researchers, students, and true crime enthusiasts seeking verified facts, case records, and deeper historical context. [Disclaimer→ WickedWe.com is an educational/entertainment column only. No graphic imagery. Victim-respect policy. Nothing herein is legal advice.]

Beyond the Gavel

Roll Card | Snapshot

  • Name: Yukio Yamaji
  • DOB/DOD: 1983-08-21 / 2009-07-28 (age 25)
  • Venue: Osaka District Court (double murder); Yamaguchi juvenile case (2000)
  • Sentence: Death (Dec 13, 2006) → Final (appeal withdrawn, 2007) → Executed (Osaka Detention House, July 28, 2009)

Docket Map | Proceedings (Condensed)

  • 2000: Matricide → juvenile disposition (Yamaguchi).
  • 2003: Paroled.
  • Nov 17, 2005: Osaka double homicide; arson.
  • Dec 5, 2005: Arrest & statements.
  • Dec 13, 2006: Death sentence (Osaka District Court).
  • Jun 2007: Appeal withdrawn; sentence finalized.
  • Jul 28, 2009: Execution (with Maeue in Osaka; third in Tokyo).

Stay / Warrant / Window (Japan Context)

Japan provides no public “warrant window” like U.S. practice; executions are conducted with limited notice under Justice Ministry authority. Notice is often same-day, criticized by rights groups. Yamaji’s execution was part of a three-person hang day on July 28, 2009.

Case File Extras | What the Record Shows

  • Victims (Osaka): Asuka Uehara (27) & Chihiro Uehara (19).
  • MO: Sexual assault (elder sister), knife murders, post-offense arson.
  • Statement: He “couldn’t forget the feeling” from the first killing and “wanted to see blood.”
  • Co-execution: Hiroshi Maeue (the “Suicide Website Murderer”) executed the same day in Osaka.

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