Kaoru Kobayashi

Kobayashi was executed by hanging at Osaka Detention Center on February 21, 2013.

Kobayashi's new lawyer claimed in June 2007 that the withdrawal was invalid, which the Nara district court declined on April 21, 2008. On May 22, 2008, the Osaka high court upheld the decision. On July 7, 2008, the Supreme Court of Japan upheld the decision.

Kaede's identity had been withheld by the Japanese media when the media learned of his sex crime, but the bereaved released her name and photograph in September 2006.

On September 26, 2006, Kobayashi was sentenced to death by hanging by the Nara district court. The defense made an appeal on the same day, but retracted it on October 10, 2006.

On January 19, 2005, Kobayashi was prosecuted for kidnapping. Because he had previous sexual offenses involving girls, public attention turned to passing a law in Japan similar to Megan's Law in the United States.

As a result of this, Mainichi Shimbun announced on January 19, 2005, that it would terminate its contracts with two delivery agents in Kawai and Higashisumiyoshi Ward in Osaka on January 31.

Kobayashi's trial began on April 18, 2005. He said:

On November 17, 2004, Kobayashi kidnapped seven-year-old Kaede Ariyama at random while she travelled from Tomio North Elementary School to her home, near the west-side police station in Tomio. Using Ariyama's cellular phone, Kobayashi sent a photograph of the girl to her mother with the message: "I've got your daughter". Kobayashi then murdered Ariyama, and dumped her body in the town of Heguri in the Ikoma District of Nara Prefecture, which was found that night. The autopsy revealed the cause of Ariyama's death to be drowning; the water collected in her lungs was not dirty, so it was assumed that she had been drowned in a sink or bathtub. Several of her teeth were missing and abrasions were found on her hands and feet, which were assumed to have been done by Kobayashi after her death. It also appeared that Kobayashi had undressed Ariyama before murdering her and then re-dressed her afterwards.

On December 14, 2004, Kobayashi sent an email from Ariyama's cellular phone to her mother's cellular phone, saying "I'll take her baby sister next" with a photograph.

On December 30, 2004, Kobayashi was arrested for kidnapping after he had sent a photograph from Ariyama's cellular phone to his own, which helped speed his arrest because the local cell phone towers logged the messages sent from the phone. Kobayashi lived in the town of Kawai in Kitakatsuragi District, located in the northwest area of Nara Prefecture along with Tomio and Ikoma, and was arrested after he had finished his morning paper route distributing the news that the suspect would be arrested soon. During a search of Kobayashi's room, the police discovered Ariyama's cellular phone and randoseru, a video and a magazine containing child pornography, and a considerable amount of girls underwear which Kobayashi had stolen between June and December 2004.

In the wake of the arrest, it was revealed that the manager of the newspaper delivery agency in Osaka's Higashisumiyoshi Ward had made a report to the police that a newspaper subscription fee of 230,000 yen had been stolen. Afterwards, the manager discovered that the thief was Kobayashi, now working in Kawai. On November 17, 2004, the day of the kidnapping, a judge had issued an arrest warrant for Kobayashi for the embezzlement reported by the manager. However, the manager did not inform the police of this, because he was promised that the suspect would repay him for the stolen money with monthly payments. Therefore, the police were not able to arrest Kobayashi, and he was free to commit his attack.

Kobayashi had worked at a newsstand for Asahi Shimbun in Tomio, a neighborhood in the west-side of Nara, between March and July 2000. At the time of the murder, Kobayashi was employed as a newspaper deliveryman for Mainichi Shimbun in the Ikoma District of Nara Prefecture, adjacent to Tomio.

The killing of Kaede Ariyama fuelled an increased hostility towards otaku culture in Japan, which had already been the subject of a moral panic since 1989, when Tsutomu Miyazaki was arrested for the murder of four girls aged between four and seven years-old. Miyazaki became known as "The Otaku Murderer" due to his strong interest in anime and horror films, sparking negative stereotypes of otaku leading people to become violent criminals, particularly against young girls. Kobayashi's crime was associated with otaku in Japanese society due to its similarity to Miyazaki's crimes.

Kaoru Kobayashi (小林 薫 , Kobayashi Kaoru, November 30, 1968 – February 21, 2013) was a Japanese newspaper deliveryman who kidnapped, sexually assaulted and murdered 7-year-old Kaede Ariyama (有山 楓 , Ariyama Kaede) in Nara on November 17, 2004. Kobayashi, an ex-convict and pedophile with a record as a prolific sex offender, was sentenced to death for the murder of Ariyama and was executed by hanging at Osaka Detention Center on February 21, 2013. Ariyama's murder caused a surge in the moral panic against otaku culture in Japan.

Kaoru Kobayashi was born on November 30, 1968, in the Sumiyoshi-ku ward of Osaka. He worked as a paperboy since his childhood as his family was poor, and his mother died in 1978. In 1989, Kobayashi was convicted of sexually assaulting eight children, receiving a suspended sentence of 2 years imprisonment. In October 1991, Kobayashi attempted to kill a five-year-old girl and was sentenced to 3 years in prison, for which he was paroled on November 9, 1995, and officially released on July 23, 1996.