Takahiro Shiraishi lured victims that contemplated suicide on the social media network and was arrested after body parts were found in his flat in 2017.
A Japanese man pleaded guilty to murdering nine people after contacting them on Twitter, in a high-profile case that has shocked the island nation.
Dubbed the “Twitter killer”, Takahiro Shiraishi was arrested in 2017 after dismembered body parts were found stored in his apartment.
The 29-year-old defendant told the Tachikawa branch of the Tokyo District Court on Wednesday that the allegations against him were “correct.”
However, his defense team argued that he killed the victims – eight women and one man aged 15 to 26 – with their consent as they had expressed suicidal thoughts on social media, and therefore Shiraishi was guilty of the lesser charge of homicide with consent.
But Shiraishi disagreed with his lawyers.
“There were bruises on the back of the victims’ heads. It means there was no consent and I did it so that they wouldn’t resist,” he said.
The court case has attracted wide interest, with more than 600 people lining up for 13 public gallery seats to watch the first hearing.
There will be a total of 24 hearings scheduled to be held over 77 days. The ruling is set to be handed down on December 15.
If convicted of murder Shiraishi faces the death penalty, which is carried out by hanging in Japan.
According to the indictment, Shiraishi strangled and dismembered his victims from Tokyo and four other prefectures, or local administrative entities, from August to October in 2017.
The serial killings first came to light in October 2017 when police officers visited Shiraishi’s apartment and found several cooling boxes containing body parts during their search for a 23-year-old missing Tokyo woman, who later turned out to be one of the victims.
The prosecution says the accused opened a Twitter account – loosely translated as “Hangman” – in March 2017 “to contact women contemplating suicide, whom he saw as easy targets.”
Shiraishi is believed to have lured his victims to his home by telling them he could help them die and, in some cases, claimed he would kill himself alongside them.
His Twitter profile contained the words: “I want to help people who are really in pain. Please DM [direct message] me anytime.”
Shiraishi is alleged to have stolen cash and sexually assaulted all the female victims. He owed one of the women around $3,410.
After months of psychiatric tests, prosecutors concluded that Shiraishi was criminally liable and indicted him in September 2018.
The killings stunned Japan when they were exposed and sparked a debate about websites on which suicide is discussed.
The murders also prompted Twitter to amend its rules to state users should not promote or encourage suicide or self-harm.
Japan has long battled one of the highest suicide rates in the industrialised world, although it has made strides in reducing its rate since the dark days of the late 1990s, when layoffs triggered by the Asian financial crisis drove annual cases over 30,000 in 1998.
Since peaking at 34,427 in 2003, it has steadily been on the decline, falling every year since 2009. Last year, the number dropped to 20,169, the lowest figure since authorities started keeping records in 1978.