A 24-year-old man, Kyota Hattori, has been arrested for injuring 17 people on a train in Tokyo on Oct. 31.
Eyewitnesses reported that he was dressed as the Joker, donning a purple suit and green shirt on the night of the attack.
Japan News reported that senior officers from the Metropolitan Police Department said that Hattori sprayed pesticide into the eye of a 72-year-old man before stabbing him in the chest with an approximately 30 centimeter long knife.
The report added that the knife pierced the victim's lung and he is currently in critical condition.
Hattori then moved to another carriage in the train, where he poured lighter fluid and set the seats on fire.
16 other individuals were injured from the incident, mainly from minor injuries and smoke inhalation.
Regretted not being able to kill anyone
In the course of the investigation, he told investigators that he adores the character Joker, a villain in Batman, Nikkei Asia reported.
According to Nikkei Asia, the police also shared Hattori saying he "wanted to kill people" and to be "given the death penalty".
Nikkei Asia also reported that the police said Hattori expressed regret at failing to kill anyone.
Planned attack as early as June
According to NHK, the police said that two hours before the attack, Hattori visited Shibuya district in Tokyo, a hotspot for partygoers to dress up in costumes to celebrate Halloween.
He told investigators that things were "not going well with work and friends" and he planned the attack as early as June.
He also referenced the Odakyu incident during the questioning, saying that he had targeted an express train which "would have more passengers". The Odakyu incident involved a man injuring 10 passengers in a random knife attack.
Hattori arrived in Tokyo last month, after losing his job in Fukuoka, and travelled eastwards.
He stayed in several major cities before reaching Tokyo.
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