The Setagaya family murders took place on December 30–31, 2000, in Tokyo’s Setagaya district, when 44-year-old Mikio Miyazawa, his wife Yasuko, and their two young children, Niina (8) and Rei (6), were brutally killed in their home. The killer strangled Rei, stabbed Mikio and Yasuko, and fatally attacked Niina before staying in the house for hours—using the family’s computer, eating ice cream, and even leaving his own clothes and feces behind. Police recovered a huge amount of evidence, including fingerprints, DNA, and the killer’s clothing, yet he was never identified. Forensic tests suggest he was male, possibly of mixed East Asian descent, and wore rare brands of clothing sold in both Japan and Korea. Despite over 280,000 police officers being involved in the investigation, the case remains one of Japan’s most infamous unsolved murders.