Police have arrested a 16-year-old girl on suspicion of bludgeoning and strangling her high school friend before hacking off the victim's head and left hand.
The shocking murder, which took place in Sasebo city, Nagasaki prefecture in western Japan, adds to the list of gruesome killings in this country, many of them committed by children.
The victim, Aiwa Matsuo, who was 15, was found dead by police early on Sunday morning on a bed in the apartment of her killer, who was living alone.
The suspect told police that she had attacked Aiwa from behind with a metallic object, and dealt her more than a dozen blows with it before tightening a rope around the girl's neck.
"I did it all by myself," the suspect was quoted as telling police.
Police also discovered many knife wounds on the torso of the dead girl, suggesting that her killer had tried unsuccessfully to cut off other parts of the body.
Aiwa was reported missing by her family when she failed to return home last Saturday evening after apparently having gone to visit her friend.
Reports quoting friends of the suspect said she was "very smart but had emotional ups and downs".
Local newspapers in Sasebo distributed special editions of news of the incident, which reminded residents of a murder in 2004 - also in Sasebo - in which a 12-year-old girl lured her victim into a classroom and slashed her on the neck from behind with a box cutter, causing a fatal loss of blood.
The killer had written on an Internet bulletin board that her victim "pretended to be a good girl and therefore I decided to kill her".
Following the 2004 incident, teachers in Sasebo's primary schools conducted classes on morality and the preciousness of life.
The local education board also tried to coach teachers in how to look for "danger signs" among children, and also established helplines for students.
The latest killing suggested that the message had not sunk in, reports quoted the principal of the school which the two girls attended as saying.
In 2003 in Nagasaki city, also in Nagasaki prefecture, residents were stunned after a mentally ill teenager kidnapped a four-year- old child and stripped him before pushing him off the top of a multi-storey carpark building, killing the boy.
But the crime paled in comparison with the 1997 child murders in Kobe city committed by a 14- year-old boy.
In one case, the teenager brutally murdered a mentally challenged 11-year-old boy.
The victim's head was mutilated before being sawn off, then left in front of a school in the city to be discovered by students arriving in the morning for classes.
The killer stuffed a note in his victim's mouth which said it was "the beginning of the game" and dared police to stop him.
He later also confessed to killing a 10-year-old girl.
Meanwhile, a slew of murders involving young women has hogged headlines in Japan in recent months.
In May, the body of a nurse, missing since late March, was found stuffed into a box marked "Doll" and sent nearly 400km across the nation without arousing the suspicions of postal workers.
Police finally caught up with the alleged killer, a 29-year-old primary school friend of the dead woman, who was detained in Shanghai after she entered China using the victim's passport.
This article was first published on July 29, 2014.
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