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Setagaya Family Murders

New releasePublished May 21, 2026Updated August 15, 2026
Dec 30, 2000

Nighttime home invasion and murders

Between 11:30 p.m. and 12:05 a.m., an intruder killed the four family members inside their home.

View sequence of events
  1. late night
    Assailant likely entered via second‑floor bathroom window adjacent to Soshigaya Park.
  2. around midnight
    Rei was strangled in his bedroom.
  3. around midnight
    Mikio confronted the intruder; he was fatally stabbed with a sashimi knife, whose blade partially broke.
  4. around midnight
    Yasuko and Niina were attacked with the broken knife and then a household santoku knife.
Dec 31, 2000

Intruder remains in the house for hours

The killer stayed inside, used the computer and bathroom, ate food, treated injuries, ransacked rooms, and left clothing and other items.

View sequence of events
  1. 01:18–01:23
    Family computer connected to the internet.
  2. overnight
    Consumed barley tea, melon, and ice cream; used first‑aid items and restroom without flushing.
  3. overnight
    Ransacked drawers; some cash taken; numerous items left behind (e.g., hip bag, clothing, knives).
Dec 31, 2000

Bodies discovered by Yasuko’s mother

At 10:40 a.m., Haruko entered the home and found the four victims, prompting a major TMPD investigation.

View sequence of events
  1. 10:40
    Haruko enters the house and discovers the four victims inside the residence.
  2. shortly after
    Police are notified and the residence is treated as a major homicide scene.
  3. same morning
    The discovery fixes the final known endpoint of the overnight attack and begins the long-running TMPD special investigation.
Jan 1, 2001

Dietary trace evidence reported

Analysis of fecal matter left at the scene indicated the suspect had eaten string beans and sesame seeds.

View sequence of events
  1. Forensic examination of fecal matter left at the scene identifies partially digested string beans and sesame seeds.
  2. after testing
    The finding reinforces the conclusion that the offender remained in the house long enough to eat and use the bathroom after the murders.
  3. Dietary trace evidence becomes one of several unusual behavioral clues used to characterize the offender's post-crime conduct.
Jan 1, 2010

Statute‑of‑limitations reform

Japan abolished the statute of limitations for crimes eligible for the death penalty; the Setagaya case was widely cited in public debate.

View sequence of events
  1. Japan abolishes the statute of limitations for crimes punishable by death, including the most serious homicides.
  2. public debate
    The Setagaya murders are widely cited as an example of why families and investigators opposed time limits on such cases.
  3. after reform
    The legal change ensures that prosecution in a case like Setagaya would no longer expire with the passage of time.
Jan 1, 2013

3D model of residence produced for investigation

TMPD used 3D printing to create a model of the house to support investigative reconstruction.

View sequence of events
  1. TMPD uses 3D printing to create a physical model of the Miyazawa residence.
  2. investigative use
    The model helps investigators visualize internal movement, entry points, and the spatial relationship between rooms.
  3. The project reflects the case's shift toward long-horizon reconstruction techniques rather than only fresh witness leads.
Jan 1, 2019

Police announce plan to demolish deteriorating house

TMPD stated the residence would be torn down due to structural concerns, noting evidence had been preserved.

View sequence of events
  1. Police announce that the deteriorating residence is planned for demolition because of structural and site-management concerns.
  2. same period
    TMPD emphasizes that investigative evidence and documentation from the scene have already been preserved.
  3. after public response
    Family members and supporters push back, and the site remains symbolically important to the case's public memory.
Dec 1, 2021

Reward increased to ¥20 million

Authorities announced a reward of up to ¥20 million for information leading to the killer’s arrest.

View sequence of events
  1. Authorities announce that the reward for information leading to an arrest rises to as much as 20 million yen.
  2. reward structure
    The total reflects a combination of public program funds and additional cooperative contributions tied to the investigation.
  3. public outreach
    The increase is meant to generate new tips in a case where abundant forensic traces still had not yielded a public identification.
Dec 17, 2021

Knife purchaser ruled out via DNA

TMPD reported a person of interest who bought the same knife model was visually identified but excluded after DNA comparison.

View sequence of events
  1. Investigators develop a lead to a person who purchased the same knife model believed relevant to the case.
  2. follow-up review
    Enhanced imaging and investigative reconstruction make the purchaser seem worth closer scrutiny.
  3. after DNA comparison
    The lead is ultimately ruled out when the person's DNA does not match the biological material recovered from the scene.
Dec 9, 2023

Public appeals at Seijōgakuen‑mae Station

TMPD conducted a flyer campaign at Seijōgakuen‑mae Station to solicit information on the case.

View sequence of events
  1. TMPD officers distribute flyers at Seijogakuen-mae Station as part of a renewed public appeal campaign.
  2. same campaign
    The outreach highlights the suspect's retained clothing and bag items as continuing identification anchors.
  3. The event shows that decades later the investigation still relies on public recognition of physical evidence and memories near the area.
May 27, 2024

Setagaya Ward motion on DNA usage

The Setagaya Ward Assembly passed a motion promoting broader investigative use of DNA evidence in Tokyo.

View sequence of events
  1. The Setagaya Ward Assembly passes a motion encouraging broader use of DNA evidence in investigations.
  2. policy framing
    The motion reflects continued local frustration that strong biological evidence in the Setagaya case had still not produced an identification.
  3. after passage
    The resolution is framed as support for expanding how DNA information can be used in Tokyo policing and cold-case work.