A male passenger in his 70s was in critical condition after being stabbed in the chest on the train, with the attack taking place as partygoers headed into the city centre for Halloween gatherings.

“With a knife he was carrying, the man stabbed the right side of the chest of a male passenger in his 70s sitting in the train, but couldn’t achieve his aim [of murder],” a Tokyo police spokesman said.

“He told police he wanted to receive a death sentence by killing someone.”

The other victims in Sunday’s incident ranged in age from their teens to their 60s. In addition to the seriously injured man, 16 people sustained minor injuries including smoke inhalation.

Top government spokesman Hirokazu Matsuno on Monday described the incident as “atrocious and brutal”.

The attacker told police he admired the Joker, local media reported. He said he had “failed in jobs and friendship and wanted to die but couldn’t die himself”, the Sankei said.

Batman’s arch-nemesis is regarded as one of the most notorious psychopaths in comic book history. The 2019 film Joker sparked criticism of its portrayal of the murderous villain as an outcast hero, with US authorities warning of copycat attacks after the movie’s release.

Before Sunday’s attack, the suspect reportedly walked around Tokyo’s Shibuya district, a busy area full of young people in Halloween costumes. He said he had worn the outfit especially for the attack.

“First I thought it was something like a Halloween event. But I rushed away as a man carrying a long knife came in. I was very fortunate not to be injured,” a man who was on the train told NHK.

The attacker carried out the act without showing any emotion, a female passenger said.

“He held a knife and started spreading liquid,” she said. “He was committing this act without showing any emotion, just mechanically. I think that brought fear to everyone.”

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The assailant reportedly said he had used a stabbing attack on a commuter train in Tokyo in August as a reference. In that attack, nine people were wounded, one of them seriously.

In a separate attack, also in August, two people suffered acid burns at a Tokyo subway station.

Japan’s worst attack on members of the public in recent decades was in 1995, when members of the Aum Shinrikyo cult released sarin gas on the Tokyo subway, killing 13 people.

Yoko Tsukamoto, a professor of nursing at the Health Sciences University of Hokkaido, said she fears that young people are under so much stress in their daily lives that similar incidents are “highly likely”.

“Because of the pandemic, young people have not been able to go out, many are doing their university courses from home or have lost their jobs and are experiencing financial difficulties,” she said.

“So they are feeling isolated and we are seeing more and more mental health problems, particularly in the 18-to-24 age group.”

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A recent study by Japan’s National Institute of Infectious Diseases found that nearly 50 per cent of people in that age group have reported some kind of mental health issue, she added.

“Their lives have changed dramatically,” Tsukamoto said.

“I sometimes go to our emergency department and I see young people who say they worry about catching the virus, they are isolating from friends and family and I’ve noticed an increase in the number of accidental overdoses of prescription medicines because people are worried about being taken ill.

“Even in a best-case scenario, with infections remaining low and people’s lives getting back to normal, it is still going to take a long time for people to heal,” she said.

The incident took place on a 10-car train bound for Shinjuku, a busy station in central Tokyo, from Hachioji in the west of the capital.

Investigative sources and eyewitnesses said the suspect was brandishing what looked like a kitchen knife and holding a plastic bottle in his other hand as he walked through the train.

After riding the train in the eighth car from the front and stabbing the man in his 70s, Hattori moved to the sixth car where he scattered the fluid and burnt a seat. The train then filled with smoke.

The limited express train made an emergency stop at Kokuryo Station in Chofu, western Tokyo, and the fire was put out about 30 minutes later after over 40 firefighting vehicles were mobilised.

“I heard a loud bang and saw flames and smoke in the back. Everyone was panicking,” a male passenger said.

Multiple photos and videos of the incident, which took place on the day of Japan’s general election, were posted on social media by eyewitnesses. People were seen climbing out of train windows on to the platform after the doors failed to immediately open when the train stopped. Screaming could be heard and someone saying, “Run away”.

Additional reporting by Kyodo