In the late 1980s, a wave of terror paralyzed Japan. It wasn’t a foreign threat or a natural disaster, but a man who lived among the stacks of thousands of videotapes, retreating into a fantasy world that eventually bled into a gruesome reality. Known as "The Otaku Murderer" and "The Rat Man," Tsutomu Miyazaki’s name became synonymous with the ultimate taboo: the cannibalization and mutilation of innocent children.
This is the investigative report into the four-year-old victims, the forensic failures, and the psychological darkness that changed Japanese society forever.
1. The Timeline of Horror: 1988–1989
Miyazaki’s spree targeted young girls between the ages of 4 and 7. His methods were calculated, involving abduction, strangulation, and post-mortem desecration.
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August 1988: 4-year-old Mari Konno disappeared.3 Miyazaki murdered her, molested her corpse, and kept her hands and feet in his closet.
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October 1988: 7-year-old Masami Yoshizawa was abducted. He murdered her in a wooded area and took her clothes as trophies.
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December 1988: 4-year-old Erika Namba was lured into his car. After the murder, he sent her family a series of taunting postcards.
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June 1989: 5-year-old Ayako Nomoto became his final victim. He dismembered her body and abandoned parts in a cemetery.
The "Cardboard Box" Incident
In a display of unparalleled cruelty, Miyazaki burned the remains of Mari Konno and placed the ashes in a cardboard box. He left the box on the doorstep of her parents' home with a note that simply said: "Mari. Cremation. Bones. Investigation. Proof."
2. The Psychology: "The Rat Man" and the Grandfather
Miyazaki was born with a physical deformity—his wrists were fused, making it impossible for him to turn his palms upward. This led to severe bullying and social isolation.
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The Loss of the Grandfather: The only person Miyazaki felt a connection to was his grandfather. When he died in 1988, Miyazaki’s fragile mental state shattered. He reportedly ate part of his grandfather's ashes in a desperate attempt to "absorb" his presence.
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The "Rat Man" Delusion: During his trial, Miyazaki gave incoherent testimony, claiming that a "Rat Man" appeared to him and forced him to commit the murders to "sacrifice" the girls and bring his grandfather back to life.
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The Fetishist: Investigators found over 5,700 videotapes in his small room, many containing slasher films and child pornography, interspersed with footage he had filmed of his own victims.
3. Institutional Failures and "Otaku" Stigma
The case is often criticized for how authorities and the media handled the investigation, leading to a "Moral Panic" that marginalized an entire generation of Japanese youth.
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Delayed Apprehension: Miyazaki was only caught by accident in July 1989 while trying to molest another girl; her father caught him and turned him in. Police had failed to link the previous four murders to him despite his proximity to the crime scenes.
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The Birth of the "Otaku" Panic: The media seized on his collection of anime and manga, co-opting the term "Otaku" (meaning geek/shut-in) and turning it into a label for a "criminal reserve army."
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Coerced Confessions: Years later, Miyazaki claimed he was physically threatened by police into confessing to the murders, highlighting the intense pressure on the Hachioji Police Station to close the case.
4. The Trial and Execution: Justice at a High Cost
The trial lasted seven years, primarily debating whether Miyazaki was legally sane.
| Phase | Outcome | Key Finding |
| First Trial (1997) | Death Sentence | Ruled sane and aware of right vs. wrong. |
| High Court (2001) | Sentence Upheld | Dismissed the "Rat Man" defense as a ruse. |
| Supreme Court (2006) | Final Verdict | Confirmed he was fully competent. |
| Execution (2008) | Hanging | Executed at the Tokyo Detention House. |
Miyazaki never apologized to the families. He spent his final years in prison writing rambling letters and drawing pictures of "The Rat Man," remaining unrepentant until the moment the trapdoor opened.
5. Data and Impact on 2025 Laws
The legacy of Miyazaki led to some of the strictest child protection and pornography laws in Asia.
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Revision of the Penal Code: Japan significantly strengthened laws regarding child abduction and the possession of harmful materials.
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Surveillance Culture: The case pioneered the use of psychological profiling in Japanese law enforcement, which was previously non-existent.
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Social Impact: The "stigma of the Otaku" lasted for decades, only beginning to soften in the mid-2010s as anime became a global mainstream export.
Was the media right to blame "Otaku" culture for Miyazaki's crimes, or was he a product of a society that failed to address severe childhood trauma?
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