TOKYO - As mourners, some weeping, piled Japanese comics, flowers and other mementoes at the scene of a deadly stabbing rampage, the government Monday sought to impose tighter controls over large knives and provide better security in public places.
News that the attacker had posted Internet messages saying he intended to kill people in the Akihabara district, the heart of Tokyo's comic book and youth culture, added to the shock as Japan struggled to make sense of the violence, which left seven people dead and 10 wounded.
"It's unbelievable that things like this are happening in our country," said 19-year-old Tsutsumo Hirano, who attended high school with one of the victims, paying respects at the makeshift memorial.
Tomohiro Kato, 25, a temporary worker at a factory outside Tokyo, was splattered with blood when he was arrested Sunday during the lunchtime attack in the crowded shopping district.
Police say Kato rammed a rented two-tonne truck into a crowd of shoppers, then jumped out and began stabbing victims who had been knocked down before lashing out at others in the crowd.
On Monday, Internet sites and the media carried a series of messages posted on an electronic bulletin board in the hours before the attack.
National broadcaster NHK said Kato posted messages under a thread titled, "I will kill people in Akihabara," and wrote: "I want to crash the vehicle and, if it becomes useless, I will then use a knife. Goodbye, everyone."
According to the NHK report, another message was sent from Akihabara by cellphone that read: "It's time," just 20 minutes before the truck hit the first pedestrians.
Authorities confirmed that Kato had posted messages, but did not release details.
Japanese authorities grappled with possible explanations for the attack, the latest in a string of assaults in recent years. Some speculated that the growing gap between rich and poor was spurring rage among have-nots like Kato; others said Japan has become a lonelier place in recent years.
"The group mentality has given away to individuality in Japan," said Nobuo Komiya, a criminologist at Rissho University in Tokyo. "This is fine for people who can deal with their problems on their own, but not for those who need someone to talk and listen."
There were signs of trouble in Kato's life. Last week, he lost his temper at the factory where he worked in Shizuoka, about 160 kilometres southwest of Tokyo, said company executive Osamu Namai.
"He was screaming that his uniform was missing. When his colleague got a new uniform for him, he had already left and never returned," Namai told reporters.
Government officials scrambled to respond to Sunday's attack. In an emergency meeting, the ruling coalition considered limiting access to knives like the one used in the stabbing, which had a 13-centimetre blade.
"Obviously, the suspect possessed the knife without a legitimate reason," said chief cabinet secretary Nobutaka Machimura. "I think we have to seriously consider what we can do to step up the restrictions."
The attack was a blow to Akihabara, once a low-cost electrical supply district that has grown over the past 15 years into Tokyo's premier computer and youth culture centre, with everything from huge multistorey electronics emporiums to cafes where youths read comic books and hostesses dress as popular animation characters.
Kato, like many Japanese young people, was fascinated with anime, Japanese animation. In a page from his junior high school yearbook published by Yomiuri newspaper, he had made a drawing of his favourite video game character holding a dagger. He wrote in English, "Personality Crooked," the report said.
There was no apparent evidence, however, linking those interests to the killing. He reportedly went to Akihabara because its main streets are closed to cars and open to large numbers of pedestrians on Sundays.
Aside from the makeshift memorial, shopkeepers and workers in Akihabara went about their business as usual Monday.
"There are a lot of reporters asking questions," said Kiyotaka Aoki, who sells mobile phones across the street from where the crimes took place. "But other than that, things are totally normal."
Sunday's killings were the latest in a string of attacks in Japan.
In March, one person was stabbed to death and at least seven others were hurt by a man who went on a slashing rampage with two knives outside a shopping mall in eastern Japan. In January, a 16-year-old boy attacked five people, injuring two.
A spate of knife attacks also occurred in schools, the worst on June 8, 2001, when a man killed eight children near Osaka. He was executed in 2004.