The 25-year-old Japanese who stabbed seven people to death in Tokyo yesterday warned about his murderous plans through several messages posted on an online notice board that ended just minutes before he went to the streets to indiscriminately kill people.

Tomohiro Kato sent as much as 30 messages from his cell phone, complaining from a headache and the fact that he was unable to make friends.

"I will kill people in Akihabara", he wrote in a Sunday morning message. "I will crash my car, and if it is destroyed, I'll use a knife. Goodbye, everyone."

He wrote more messages as he drove the 60 miles from his home in Susono, in the foothills of Mount Fuji, to Akihabara, a district of Tokyo known as the centre of Japan's geek subculture. When he arrived there he crashed his car into a group of shoppers and then got out of the vehicle with a long dagger and stabbed everyone in his path.

Authorities said Kato killed seven people - six men and one woman – and wounded 10 other, who are now being treated at the hospitals.

Kato drove the vehicle into the shoppers walking on a street closed to traffic on Sundays. The street was packed with pedestrians drawn by discounts at electronics stores. Kato knew the area very well and also knew the street would be packed with people.

"It's heaven for pedestrians, isn't it?" he wrote in a message.  At 12:10 he sent the final message: "It's time." 20 minutes after, he began the killing spree, the worst attack of its kind in Japan for seven years.

Seven years ago, a janitor from a Japanese primary school killed eight children with a knife. He was executed in 2004 . In January, a 16-year-old boy attacked 5 people, also with a knife, and injured two of them. In March, a man at a railway station injured 8 people with a knife, BBC reported.