Yukio Yamaji was born on August 21, 1983, in Shimonoseki, Yamaguchi, Japan. He grew up in a poor family. His life changed dramatically when his father passed away from cirrhosis in January 1995. This loss put additional stress on his family.

After finishing junior high school, Yamaji dropped out. He began working at a newspaper store to help support himself and his family. His early years were marked by challenges, and he struggled to find stability in his life.

Yukio Yamaji committed his first murder on July 29, 2000, when he killed his 50-year-old mother with a metal baseball bat in Yamaguchi city, Yamaguchi Prefecture. After the murder, he called the police and was arrested two days later, on July 31, 2000. He stated that his motives were linked to his mother’s silent telephone calls to a woman he loved and her increasing debt. He received parole in October 2003.

Just two years later, on November 17, 2005, Yamaji committed a double homicide. He raped and murdered 27-year-old Asuka Uehara and her 19-year-old sister, Chihiro, using a knife in their apartment located in Naniwa, Osaka. After the murders, he set their apartment on fire and fled the scene. Yamaji had never met either victim before. He was arrested on December 5, 2005. While in police custody, he mentioned that he wanted to feel the experience of killing again and could not forget the feeling from when he killed his mother.

On December 13, 2006, the Osaka District Court sentenced Yukio Yamaji to death for his crimes. His defense team appealed the sentence, but he later retracted the appeal, refusing to seek leniency. Yamaji was executed by hanging on July 28, 2009, at the Osaka Detention House.