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Amagasaki Serial Murder Incident

SOLVED2008Amagasaki City, Hyogo Prefecture, Japan3 SOURCESUPDATED JUL 2026
Illustrative

Between approximately 1987 and 2011, Miyoko Sumida, a woman from Amagasaki City in Hyogo Prefecture, Japan, allegedly built a "pseudo-family" of people unrelated to her by blood, drawing them in through relationships, forced marriages, and adoptions. According to the case record, Sumida is alleged to have exercised absolute control over this group, using intimidation and exploitation of personal weaknesses to dominate multiple families she and her associates became involved with in Amagasaki and six other prefectures — Hyogo, Kochi, Kagawa, Okayama, Shiga, and Kyoto.

The pattern reportedly began with the disappearance of a woman, Yoshiko Hashimoto, around 1987, followed by a series of suspicious deaths and disappearances involving multiple families over the following decades, including cases referred to in case documents as the "A," "B," "C & D," and "E & F" family matters. At least eight deaths were confirmed, largely attributed to assault, confinement, and related abuse. Members of the pseudo-family were reportedly forced to participate in violence against their own relatives, deprived of food, drink, and sleep, stripped of property, and compelled to break apart their families of origin.

The case came to public attention in November 2011 when a woman in her 40s who had been held captive escaped confinement and went to police. Sumida was arrested on suspicion connected to the death of one victim's eldest daughter. A subsequent theft case involving pension withdrawals led an accomplice to confess further details, and investigators went on to discover multiple bodies, including remains found in a drum can, underneath floorboards of a house, in a farm equipment shed, and in the sea off Okayama Prefecture, between late 2011 and December 2012.

On 7 November 2011, Sumida and seven others were arrested. Investigations continued through 2012 and 2013, involving repeated re-arrests of Sumida and other suspects — referred to in case records by letters such as H, K, I, and N — on suspicion of manslaughter, murder, confinement, insurance fraud, and abandonment of bodies. In total, 17 people were arrested or referred to prosecutors in connection with the case, a notably high number among Japanese mass-murder cases. Eleven people, including Sumida and her relatives, were ultimately indicted on manslaughter and murder charges relating to six of the eight confirmed deaths.

On 13 December 2012 (referred to elsewhere in case documents as 12 December 2012), Sumida died by suicide in a holding cell at Hyogo Prefectural Police Headquarters while in detention and reportedly on suicide watch, after having made statements to lawyers and detention staff indicating suicidal ideation. Because of her death, she was never tried; trials proceeded against ten of her relatives and associates. Her body was cremated in Kobe City on 19 December 2012, and no relatives came forward to claim her remains. A joint investigation by Hyogo, Kagawa, and Okinawa prefectural police was disbanded in March 2014. The whereabouts of three people connected to Sumida's group remain unknown.

Key facts

Victims
On file
Date
2008
Location
Amagasaki City, Hyogo Prefecture, Japan
Case status
solved

Case timeline

  1. 1987

    Disappearance of Yoshiko Hashimoto, marking the reported start of the pattern of disappearances and deaths associated with the case.

  2. 1998-03

    Reported start of a dispute over a funeral involving one family (referred to as the B family), leading to demands for money from relatives.

  3. 2000

    Miyoko Sumida and a female cohabitant reportedly became joint debtors after purchasing a condominium together.

  4. 2001

    A member of the pseudo-family (referred to as H) was married, on Sumida's orders, to another family's eldest son.

  5. 2008-11

    Reported death of Miyoko Sumida's female cohabitant, later leading to confinement charges against seven people.

  6. 2009-04

    Reported start of a family hijacking case involving families referred to as E and F, continuing to November 2011.

  7. 2011-07

    Reported death and abandonment of the body of the second son of the A family.

  8. 2011-09-11

    Reported death and abandonment of the body of F's mother.

  9. 2011-11-07

    Miyoko Sumida and seven others arrested; Hyogo Prefectural Police found a drum can containing a victim's (F's) body in a rental house in Amagasaki City.

  10. 2011-11-26

    Sumida and others arrested on suspicion of abandoning F's body.

  11. 2012-08

    Investigators found a person referred to as C hiding in Amagasaki City under a false name; testimony led to re-arrests on theft charges related to pension withdrawals.

  12. 2012-10

    Bodies of D's eldest daughter, D's brother-in-law, and a victim referred to as G discovered under floorboards of a house in Amagasaki City.

  13. 2012-12-03

    Body of C's mother discovered in a farm equipment shed in Takamatsu City.

  14. 2012-12-05

    Sumida and seven others re-arrested on suspicion of confinement and murder of A's second son.

  15. 2012-12-12

    Miyoko Sumida died by suicide in a holding cell at Hyogo Prefectural Police Headquarters while in detention.

  16. 2012-12-19

    Sumida's body cremated in Kobe City; no relatives came to claim the remains.

  17. 2012-12-30

    Body of A's second son found in the sea in Okayama Prefecture.

  18. 2013-02-04

    Suspects referred to as K, I, and seven others arrested on suspicion of confining and murdering D's eldest daughter.

  19. 2013-03-06

    Suspects re-arrested on suspicion of confinement and manslaughter of G.

  20. 2013-05-21

    Suspects re-arrested for the murder of A's eldest son.

  21. 2013-06-26

    Suspects arrested on suspicion of committing insurance fraud on A's eldest son.

  22. 2013-09-25

    Suspects arrested on suspicion of manslaughter of D.

  23. 2014-03

    Joint investigation by Hyogo, Kagawa, and Okinawa prefectural police disbanded, effectively ending further investigation.

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People

  • Mieko Sumida

    CONVICTED

    Member of Sumida's pseudo-family; convicted and sentenced to two years for pension theft, later sentenced to 21 years for murder and other crimes against two victims.

  • Jeong Raitaro

    CONVICTED

    Long-term partner of Sumida; convicted of murder in relation to two victims and of inflicting bodily injury in relation to a third, sentenced to 21 years.

  • Miyoko Sumida

    CHARGED

    Alleged leader of a pseudo-family accused of coercing others into confinement, abuse, and killings for financial gain; charged with manslaughter (later dismissed) and, following her death, further charged with manslaughter and murder relating to several victims; died by suicide in detention before trial.

Roles reflect public records and court outcomes at the time of writing — supporting citations are on file under Sources.

Places

Amagasaki City, Hyogo Prefecture, Japan

34.7333, 135.4167

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Common questions

What happened to the victim?
A pseudo-family led by Miyoko Sumida in Amagasaki, Japan, is alleged to have coerced relatives and cohabitants into confining, abusing, and killing at least eight people between 1987 and 2011 for financial gain; Sumida died by suicide in detention before trial, while ten co-defendants were tried.
Where did the murder happen?
Amagasaki City, Hyogo Prefecture, Japan.
Who was convicted?
Mieko Sumida (Member of Sumida's pseudo-family; convicted and sentenced to two years for pension theft, later sentenced to 21 years for murder and other crimes against two victims.) and Jeong Raitaro (Long-term partner of Sumida; convicted of murder in relation to two victims and of inflicting bodily injury in relation to a third, sentenced to 21 years.).
What is the current status of the case?
Status: solved.
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Sources

  1. ENCYCLOPEDICAmagasaki Serial Murder IncidentWikipedia · 2026-07-10
  2. PRESSMiyoko Sumida dies in Japan before her murder trialnews.com.au · 2026-07-10
  3. PRESSContemporaneous coverage of the Amagasaki casekobe-np.co.jp · 2026-07-10