Killing of Satomi Mitarai

The "Sasebo slashing" (Japanese: 佐世保小6女児同級生殺害事件, Hepburn: Sasebo shōroku joji dōkyūsei satsugai jiken), also known as the Nevada-tan murder, was the murder of a 12-year-old Japanese schoolgirl, Satomi Mitarai (御手洗 怜美, Mitarai Satomi), by an 11-year-old female classmate, "Girl A" (a common placeholder name for juvenile female criminals in Japan). The murder occurred on June 1, 2004, at an elementary school in Sasebo, Nagasaki Prefecture. The murderer slit Mitarai's throat and arms with a box cutter.

The killer's name was not 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. Members of the Japanese Internet community 2channel read a name on a classroom drawing believed to be made by Girl A, and publicized the name on June 18, 2004.^{[not in body]}

The incident sparked discussions about lowering the age of criminal responsibility in Japan.

On June 1, 2004, at Okubo Elementary School in Sasebo, Nagasaki Prefecture, Girl A called a 12-year-old classmate, Satomi Mitarai, to an empty classroom. Girl A slit Satomi's throat and arms with a box cutter, and reportedly watched her bleed to ensure her death. She returned to her classroom with her clothes covered in blood. Her teacher checked her arms and hands for wounds; she found none and demanded an answer. Girl A allegedly responded, "It's not my blood. It's not me." The teacher then discovered the body.

After being taken into custody, Girl A reportedly 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 confessed that she and Mitarai used to be close friends, but their relationship ended as a result of messages left on the (now deactivated) chatroom site Cafesta. Girl A claimed that Mitarai slandered her by commenting on her weight and calling her a "goody-goody".

On September 15, 2004, disregarding her young age, a Japanese Family Court ruled to institutionalize Girl A because of the severity of the crime. She was sent to a reformatory facility in Tochigi Prefecture. The Nagasaki family court originally sentenced Girl A to two years of involuntary commitment; the sentence was extended by two years in September 2006, following a psychological evaluation. On May 29, 2008, local authorities announced that they did not seek an additional sentence.

Because of her issues with communication and obsessive interests, Girl A was diagnosed after the murder with Asperger syndrome.

The killing provoked a debate in Japan whether the age of criminal responsibility, lowered from 16 to 14 in 2000 due to the 1997 Kobe child murders, needed to be lowered again. Girl A was considered to be a normal and well-adjusted child before the incident, which made the public more anxious.