A Japanese man dubbed the "Twitter killer" for luring his victims on social media has admitted in court to murdering nine people, local media said.

But lawyers for 29-year-old Takahiro Shiraishi argued the charges should be reduced because the victims gave their consent to be killed.

Mr Shiraishi, who is also accused of dismembering his victims and storing body parts in cool boxes, did not contest nine counts of murder, saying they "are all correct", public broadcaster NHK reported.

He is also facing rape charges, according to media reports.

Mr Shiraishi is accused of using Twitter to contact victims aged between 15 and 26 who posted online about taking their own lives, telling them he could help them in their plans - or even die alongside them.

If convicted of murder, he faces the death penalty, which is carried out by hanging in Japan.

Police searching Takahiro Shiraishi's home on 2 November 2017

But Mr Shiraishi's lawyers want the charges against him reduced to "murder with consent", which carries a prison sentence of between six months and seven years.

In an interview with the Mainichi Shimbun daily newspaper, he said he disagreed with his lawyers and would tell prosecutors that he had "killed without consent".

"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 in comments published today.

Mr Shiraishi was detained three years ago by police investigating the disappearance of a 23-year-old woman who had reportedly tweeted about wanting to kill herself.

After she went missing, her brother apparently gained access to her Twitter account, and noticed a suspicious handle.

Police found nine dismembered bodies and body parts in his home in the city of Zama on 31 October 2017.

Mr Shiraishi told the Mainichi Shimbun he "didn't plan on getting caught" and boasted of not being identified until his final killing.

More than 600 people lined up for 13 public gallery seats to observe today's first hearing in the case, NHK said.