(CNN) -- A 16-year-old Japanese girl has been arrested in Sasebo, Nagasaki prefecture, on suspicion of murdering a fellow student. Police confirmed that the alleged attacker also dismembered her victim's body.
The girl, who cannot be named as she is a minor, is suspected of hitting Aiwa Matsuo, 15, with an object repeatedly before strangling her.
The victim's family said that she had gone to meet friends Saturday afternoon and alerted police when she did not return later that evening.
The teen admitted killing Matsuo, and told police she acted alone. The teen, who turned 16 the day of her arrest, admitted to dismembering the body, including decapitation and severing her left hand.
The English-language Japan Times reported that the alleged attacker's "friends and acquaintances" described her as "very smart, with emotional ups and downs."
It has been reported that her father remarried after the suspect's mother died last year and lives elsewhere in the southwestern Japanese city.
At a press conference, the principal of the school that both attacker and victim attended said that the institution was not aware of any trouble between the two.
"I have no words to say now. I am overwhelmed by sadness, regret and various feelings," he said.
Reports indicate that the body was discovered early Sunday morning on a bed at the girl's apartment, where she lives alone. Implements used in the attack were found on, and next to, the bed.
Despite Japan's deserved reputation for safety and a relative lack of violent crime in the country, it is not the first time that Sasebo has appeared in headlines featuring violence perpetrated by minors -- in 2004, an elementary school-aged girl in the city killed a classmate, slashing her throat.