← Back to Japan casesKasan Allegedly Murdered by Susumu Terauchi, Hakata, Fukuoka, Japan
Case Summary
According to the video report, Susumu Terauchi stalked and harassed his former girlfriend, Kasan, after she attempted to end their relationship. Kasan consulted police, and an emergency restraining order was issued under Japan's Anti-Stalking Law. On January 16, 2023, Terauchi encountered Kasan near Hakata Station, chased her for approximately 173 meters, and stabbed her repeatedly in the chest and head, reportedly at least 17 times. He fled to an internet café, used a false name, and was arrested two days later. The source reports that he was later sentenced to 20 years in prison, while the court found the alleged waiting-in-ambush issue insufficiently proven.
Basic Information
Country: Japan
State/Province: Fukuoka, Japan
City/Region: Hakata
Incident Type: Murder
Relationship Status: Dating
Relationship Duration:
Incident Date: Jan. 16, 2023
Relationship Journey
Relationship Origins:
- Met at Workplace
- Friends circle
Relationship Stages:
- Dating
- Separated
Analysis
Contributing Factors:
- Domestic Conflict
- Mental instability
- Family pressure
Red Flags:
- Excessive phone usage
- Secretive communication patterns
- Unusual closeness with a specific third person
- Meeting people privately / hiddenly
- Escalation Pattern / Violence
- Threats
- Stalking / Repeated Harassment
- High-Conflict Household
Motives:
- Revenge
- Jealousy
- Control/domination
Relationship Outcomes:
- Homicide before marriage
- Arrest made
- Relationship ended
Source Video
Video hosted by YouTube · Viewer discretion advised
People Link Graph
Kasan Allegedly Murdered by Susumu Terauchi, Hakata, Fukuoka, Japan
Relationship Journey Graph
Origin
- Met at Workplace
- Friends circle
How the relationship or connection began.
Status
- Dating
Stages
- Dating
- Separated
Important relationship phases recorded for this case.
Warning Signals
- Excessive phone usage
- Secretive communication patterns
- Unusual closeness with a specific third person
- Meeting people privately / hiddenly
- Escalation Pattern / Violence
- Threats
- Stalking / Repeated Harassment
- High-Conflict Household
Reported red flags or early concern points.
Pressure Points
- Domestic Conflict
- Mental instability
- Family pressure
- Revenge
- Jealousy
- Control/domination
Contributing factors and possible motives from the available sources.
Incident
2023-01-16
Outcome
- Homicide before marriage
- Arrest made
- Relationship ended
Recorded relationship or case outcome.
AI Intelligence Assessment
Relationship Pattern
Domestic Violence
Pattern Analysis
The reported pattern involved a dating relationship that became coercive and dangerous after Kasan attempted to end it. Terauchi reportedly monitored her location, refused to accept the breakup, continued contacting her despite police intervention, and confronted her after a restraining order was issued. The conflict escalated from stalking and threats to a fatal physical attack.
Investigative Notes
The source reports that Kasan consulted police in October 2022 and that an emergency restraining order was issued under the Anti-Stalking Law. Terauchi allegedly continued contacting her, appeared at her workplace in disguise, and later confronted her near Hakata Station. After the stabbing, he reportedly fled to an internet café under a false name and was arrested on January 18, 2023. At trial, the prosecution argued that he had lain in wait along Kasan's route home, while the defense claimed he had been at the station to pay a phone bill and carried the knife for self-defense. The court reportedly found the stalking and pursuit unlawful but said decisive evidence of a planned ambush was lacking. Terauchi was sentenced to 20 years in prison.
Investigation Confusion
The central dispute was whether Terauchi had deliberately waited for Kasan near Hakata Station or encountered her accidentally. Terauchi denied lying in wait, while prosecutors argued that he was positioned along her route home. The source also reports conflicting explanations for his presence and the knife, including his claim that it was for self-defense. His statements blaming Kasan for refusing reconciliation were reported as self-justifying.
Case Reconstruction / Puzzle Pieces
The source presents Terauchi and Kasan as coworkers in related restaurant businesses who began a secret relationship because their employer prohibited employee dating. Terauchi reportedly became jealous and used a smartphone application to track Kasan's location. After an intoxicated confrontation in October 2022, Kasan attempted to end the relationship, consulted police, and became the subject of workplace and legal protection measures. Terauchi allegedly continued contacting and pursuing her, then encountered her near Hakata Station on January 16, 2023, chased her for approximately 173 meters, and stabbed her repeatedly. His flight, use of a false name, arrest, disputed account of the encounter, and subsequent trial formed the later investigative and legal narrative.
Risk Assessment
The source describes a high-risk escalation pattern involving persistent stalking, location monitoring, refusal to accept separation, threats, disguised workplace confrontation, repeated contact despite a restraining order, and weapon possession. The reported pursuit and repeated stabbing indicate severe imminent-danger indicators. The source does not establish whether additional protective measures or risk assessments were considered before the homicide.
Key Takeaways
The source highlights persistent stalking, digital location monitoring, refusal to accept a breakup, threats, workplace confrontation, and continued contact despite a restraining order as major warning signs. The reported escalation shows how relationship control and grievance can progress into lethal violence when separation is not respected. The case also illustrates the investigative difficulty of proving intent and premeditated waiting when direct evidence is limited.
AI Case Q&A
What early signals mattered most?
The most important reported signals were location monitoring through a smartphone application, jealousy, unwanted contact, intoxicated harassment, refusal to accept the breakup, repeated messages, threats of long-term hatred, and an uninvited workplace confrontation while disguised. The emergency restraining order and continued contact afterward indicated ongoing risk.
Which clues helped connect the case?
Reportedly important clues included Kasan's prior police consultation, the restraining order, messages sent by Terauchi, his appearance at her workplace, the station confrontation, the approximately 173-meter pursuit, the knife attack, his flight to an internet café, use of a false name, and his arrest while disguised.
Which evidence types appeared strongest?
The source indicates that the strongest evidence included the reported pursuit and attack, the restraining-order history, communications, the victim's prior report, witness or investigative reconstruction of the station encounter, and Terauchi's later statements. The court reportedly found the stalking and pursuit established but considered decisive proof of a planned ambush absent.
Witness / Eyewitness Statements
The source reports that Kasan told friends about Terauchi's suspicious behavior and told him to stop calling her. During the final encounter, she reportedly asked to discuss the matter at a police station. Kasan's mother described the family's loss in court and said Kasan had supported their lives; she also reported that Kasan's daughter was too shocked to attend school. No independent eyewitness quotation is provided.
How did follow-up reports change the understanding?
Follow-up reporting in the source moved the case from a stalking investigation to a homicide prosecution. Later investigation and trial accounts introduced the disputed issue of whether Terauchi had waited for Kasan, while the defense offered alternative explanations for his presence and knife. The source reports that the final sentence was 20 years, with the court describing his remorse as superficial.
What remained unclear?
The source leaves unclear whether Terauchi deliberately lay in wait at Hakata Station, because the court reportedly found no decisive evidence on that point. It also does not establish the complete contents or provenance of all messages, the full police risk-management process, or whether any additional witnesses directly observed the stabbing.