A man who attacked passengers on a crowded Tokyo train on Halloween night in 2021 while dressed as the Joker was sentenced to 23 years in prison on Monday for stabbing one of them and lighting a fire.

The Tachikawa branch of the Tokyo District Court found that Kyota Hattori, 26, stabbed an elderly man with a knife in his chest and also attempted to kill 10 other passengers by splashing lighter fluid around and igniting it on a Keio Line train around 8 p.m. on Oct. 31, 2021.

Prosecutors, who demanded 25 years in prison, tried to prove the attempted murder of 12 passengers by arson.

Police officers inspect a Keio Line train in Tokyo's Inagi on Nov. 1, 2021, a day after a man was arrested in a knife and arson attack that injured 17 people on the train. (Kyodo) ==Kyodo

But the court excluded two of the 12. "There remains a reasonable doubt that (the two) were at a place where their lives may have been in danger" when the fire was started, Presiding Judge Yu Takeshita said in handing down the ruling.

Hattori and his defense admitted to the stabbing and arson but disputed the number of passengers threatened by the fire.

Prosecutors argued that he planned to kill indiscriminately with the stated intent to get the death penalty and that "his motive was extremely selfish and deserving of strong condemnation."

The stabbed man was briefly in critical condition, and his injury required around three months of treatment.

During the trial, Hattori said he wanted to go on a killing spree to receive the death penalty as he felt his life was worthless.

The judge said Hattori's suicidal thoughts grew after he broke up with his fiance and she married another man, and that he was also depressed at work after being transferred from a familiar department.

Hattori "was desperate and decided to commit suicide," the judge said, adding he "thought that receiving a death penalty was the only way and prepared (the train attack) carefully."

He said earlier during the trial that he "lost my sense of existence and thought there was no point in living."

Hattori said his actions were inspired by a similar random knife attack in August of the same year on an Odakyu Electric Railway commuter train in which a man stabbed three passengers. That assailant was sentenced to 19 years in prison on July 14.

"It is a rare case where isolation and the experience of loss led to thoughts of murder-suicide and indiscriminate stabbing," Tamami Katada, a psychiatrist, said. But she also said such an experience could happen to anyone.

Katada points to the need for setting anonymous consultation services to deal with personal affairs, including for people who have lost someone close, and enhancing safety nets for those who need economic assistance. "I want people to rely on medical institutions before they overthink."

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