At the end of October 2017, police in Kanagawa Prefecture were looking for a missing 23-year-old woman. She had posted on social media about wanting to die. Her brother got into her Twitter account and found her messages with a man who had offered to help her. The trail led to a small one-room apartment in Zama, a city about 90 minutes from central Tokyo. On October 31, inside, officers found the remains of nine people.
The tenant was Takahiro Shiraishi, 27. According to reports at his trial, he had worked as a scout for the sex industry in Tokyo's Kabukicho district, recruiting young women, and by 2017 he was unemployed. He used two Twitter accounts to find people, mostly young women, who had posted about suicide. One presented him as a kind of guide who could help people end their lives; the other as a lonely man looking for someone to die with. On Twitter he called himself "Hangman." He told the people he contacted that he could help them carry out their plans or even die with them, and he invited them to his apartment.
Between August and October 2017 he killed nine people in that apartment: eight women between 15 and 26 years old and one man. Most of the women had written online about wanting to die. The man was the boyfriend, or by another account an acquaintance, of one of the women, and Shiraishi killed him because he feared he was getting close to discovering what had happened to her. The first to die was a 21-year-old woman, who was killed, he later said, after she asked him to repay money she had lent him.
Most English-language reports have not given the victims' names. Al Jazeera named the woman whose disappearance led police to the apartment as Aiko Tamura.
Shiraishi gave the women alcohol, tranquilizers and sleeping pills, raped them and strangled them. He killed the later victims, he said, because he feared they would report his assaults. He took their money. He dismembered the bodies in the apartment, disposed of some remains and kept others in cooler boxes and storage containers. Investigators recovered nine heads and about 240 bones.
Shiraishi was arrested on October 31, 2017.
The case led to a public discussion in Japan about suicide and social media. Within days of the arrest Twitter changed its rules to prohibit promoting or encouraging suicide and self-harm, and the government announced that it would take measures to prevent a repeat. Twitter's chief executive, Jack Dorsey, told NHK it would be unrealistic to remove every tweet expressing a wish to die, and the company said it would focus on directing users to suicide prevention organizations. Al Jazeera reported that nearly 22,000 people had died by suicide in Japan in 2016, the lowest figure in 22 years but still the highest rate in the Group of Seven, and that suicide was the leading cause of death for people aged 10 to 19. Suicide-prevention researchers argued that people who posted such thoughts needed help reaching support, not censorship.
Shiraishi's trial at the Tachikawa branch of the Tokyo District Court ran to 23 hearings. He pleaded guilty to all the charges, and the dispute was over his responsibility. His lawyers argued that the victims had wanted to die and consented to being killed, so that the crimes should be treated as murder with consent, which carries a lighter penalty, and that he might have had diminished capacity. Shiraishi contradicted his own defense. He said he had killed the victims without their consent and that he had done it "for financial reasons and to satisfy my sexual desires." He refused to answer many of his lawyers' questions and called their conduct an "act of betrayal."
Prosecutors pointed to the victims' resistance and to statements to relatives showing that they wanted to live, and to five months of psychiatric testing that found him mentally competent. Shiraishi apologized to some of the bereaved families in court, without meeting their eyes. He said he felt remorse about some of the victims but little about others, and that he was sorry mainly because he had been caught.
On December 15, 2020, Presiding Judge Naokuni Yano sentenced him to death. "None of the victims agreed to be killed," he said. "The defendant was found to be fully responsible." He said the crime had caused fear and concern in a society where social media had become part of everyday life. Shiraishi had said he would accept the death penalty. An appeal his lawyer filed with the Tokyo High Court was withdrawn, and the sentence became final.
Japan announces executions only after they have taken place, and prisoners are told only hours beforehand. On June 27, 2025, Takahiro Shiraishi, 34, was hanged at the Tokyo Detention House. It was the first execution in Japan since July 2022 and the first under Prime Minister Shigeru Ishiba's government.
Justice Minister Keisuke Suzuki said he had signed the order after careful consideration. He described Shiraishi's motive as "extremely selfish," driven by sexual and financial gratification, and said the crimes had "caused great shock and unrest to society." "It is not appropriate to abolish the death penalty while these violent crimes are still being committed," he said. He said 105 people remained on death row.
The father of one of the victims told NHK that he would rather have seen Shiraishi "spend his life reflecting on the crimes he committed, than simply losing it through death penalty."