The "Sasebo slashing", also known as the Nevada-tan murder, was the murder of a 12-year-old Japanese schoolgirl, Satomi Mitarai, by an 11-year-old female classmate referred to as "Girl A" (a common placeholder name used for female criminals in Japan). The murder occurred on June 1, 2004, at an elementary school in the city of Sasebo in Nagasaki Prefecture. The murderer slit Mitarai's throat and arms with a box cutter.
Reactions to the incident included Internet memes and a discussion of lowering the age of criminal responsibility in Japan. The killer's name has not been released to the press, as per Japanese legal procedures prohibiting the identification of juvenile offenders; the Nagasaki District Legal Affairs Bureau cautioned Internet users against revealing her photos. However, the girl's name was accidentally revealed on a Fuji TV broadcast, and members of the Japanese Internet community 2channel publicized her identity on June 18, 2004, based on analysis of a picture broadcast on television.
On June 1, 2004, an 11-year-old schoolgirl, later dubbed "Girl A", murdered her 12-year-old classmate, Satomi Mitarai, in an empty classroom during the lunch hour at Okubo Elementary School in Sasebo, Nagasaki Prefecture. Girl A returned to her classroom, her clothes covered in blood. The girls' teacher, who had noticed that both girls were missing, stumbled upon the body and called the police.
After being taken into custody, Girl A was reported to have confessed to the crime, saying "I am sorry, I am sorry" to police officers. She spent the night at the police station, often crying, and refusing to eat or drink. Girl A initially mentioned no motive for the killing. Shortly afterward, she confessed to police that she and Mitarai had quarreled as a result of messages left on the Internet. Girl A claimed that Mitarai slandered her by commenting on her weight and calling her a "goody-goody".
On September 15, 2004, a Japanese Family Court ruled to institutionalize Girl A, putting aside her young age because of the severity of the crime.