A teenage girl from Japan has been arrested after allegedly killing and dismembering one of her friends and posting about it on a popular message board.

The Japan Times reports the incident took place in the Japanese city of Sasebo, a part of the Nagasaki prefecture. The attacker, whose name has not been released, killed Aiwa Matsuo with a series of violent blows to the head and strangulation. After killing Matsuo, the perpetrator dismembered the body by cutting off the victim's head and her left hand. The victim was 15 and the killer was 16.

The attack took place around 8 p.m. Saturday, July 26.

Matsuo's parents called police that same night, after she did not return home from playing with friends as she had promised her parents she would.

Most chillingly, a different report from the Times suggests that the killer posted about the murder in real time on a popular Japanese message board called 2 Channel.

It is most similar to the U.S.-based 4Chan, with anonymous posting that nurtures an "anything goes," type of atmosphere.

In a post titled, "I have ended up killing," the murderer seems to share gory and explicit details of the crime.

One message in the thread read, "Oh no, blood keeps pouring out even though I have wiped it away many times."

Another, "I've tried to warm (the body) as it got cold, but it doesn't warm up. . . . Everyone, (do you want to know) what color the brain is? I'll take good care of the brain and the spinal cord, putting them in a solution."

Photos of a hand and cloth covered in blood accompanied the haunting messages. The hand appeared to belong to that of the killer, according to the Times.

The killer confessed to the crime shortly after the police arrested her.