Endo Ki, a juvenile from Chuo City, Yamanashi Prefecture, developed an obsessive one-sided love for a female classmate, Inoue, which escalated into stalking and ultimately a violent arson-murder attack on her family. After being rejected and blocked by Inoue, Endo planned and executed a break-in at her home on October 12, 2021, stabbing Inoue's father to death, severely injuring her sister, and killing her mother before setting the house on fire. Inoue and her sister escaped. Endo fled but surrendered voluntarily about 15 hours later. He was charged as an adult due to the severity of the crime.
Country: Japan
State/Province: Yamanashi, Japan
City/Region: Chuo City
Incident Type: Domestic Violence Homicide
Relationship Status: One-sided love
Relationship Duration:
Incident Date: Oct. 12, 2021
Relationship Origins:
Relationship Stages:
Contributing Factors:
Red Flags:
Motives:
Relationship Outcomes:
How the relationship or connection began.
Important relationship phases recorded for this case.
Reported red flags or early concern points.
Contributing factors and possible motives from the available sources.
2021-10-12
Recorded relationship or case outcome.
English labels are shown first. Original-language titles are preserved for source verification.
ゆっくりミステリー事件簿 · Original language: Japanese
Juvenile Crime Incident in Yamanashi
Jealousy
The case involves a juvenile offender whose obsessive one-sided love and stalking behavior toward a female classmate escalated into violent domestic homicide and arson. The offender's inability to accept rejection and his delusional belief of betrayal triggered the attack on the victim's family, reflecting a pattern of jealousy and domestic violence.
Police identified Endo Ki via security camera footage near the victim's home. He surrendered voluntarily approximately 15 hours after the incident. Initially charged with injury to the sister, later formally charged with arson murder and related offenses. Tried as an adult due to severity and recent juvenile law revision. Investigation included establishing motive, planning, and sequence of events.
No significant confusion reported; suspect identified via footage and confession. Some uncertainty about exact method of break-in.
Endo Ki developed obsessive feelings for Inoue, joined her clubs, and became student council president to get closer. After rejection and blocking, he began stalking and sending unwanted gifts. He planned a violent attack involving stabbing and arson. On October 12, 2021, he broke into Inoue's home, killed her parents, injured her sister, set the house on fire, and fled. Inoue and her sister escaped. Police identified and arrested Endo after his voluntary surrender.
High risk due to obsessive stalking, escalating threats, and violent planning culminating in murder and arson. Early signs of mental instability and social withdrawal were present.
Obsessive one-sided love can escalate to lethal violence if rejection is not accepted. Early behavioral changes, social withdrawal, and stalking are critical warning signs. Family dynamics and parental criminal history may contribute to risk. Prompt police response and surveillance footage were crucial for suspect identification.
Endo's sudden behavioral changes, social withdrawal, obsessive focus on Inoue, excessive communication with mother, and stalking behaviors were early signals.
Security camera footage near victim's home, Endo's social and school activities, and witness reports of stalking and unwanted gifts helped connect the case.
Security camera footage, physical evidence of stabbing and arson, victim and witness statements, and Endo's confession were strongest evidence types.
Not reported.
No follow-up reports beyond initial charges and juvenile law revision were available.
Exact method of break-in remains unclear.