Japan's grim reputation as one of the world's suicide nations has been confirmed by statistics that show more than 30,000 people a year have taken their own lives since figures first began to rise in 1998. In 2006, there were 32,115 suicides - 25 per 100,000 people; nearly 100 people a day; one every 15 minutes. The most common hour of death is 5am for men and noon for women, after their families have left for work or school.

Japan has roughly half the population of the US, yet the same number of suicides. There were 5,554 suicides of people aged 15 and over in the UK in 2006; three quarters involved men.

Experts in Japan were puzzled when the suicide rate jumped in 1998 from 24,391 to 32,863 - a 35 per cent rise - and the annual figure has continued to stay above 30,000. Two theories have been put forward by the media: bullying at school and netto shinju - online suicide pacts.

The world's first internet suicide pact involving strangers took place in Japan in 2003. The bodies of three young people were discovered in a van on a mountain road. The windows were sealed with black duct tape and a burnt-out charcoal stove was found inside.

Police across Japan began to make similar discoveries: three or four bodies, victims usually in their late teens to mid-twenties, and often a burnt-out charcoal stove.

Last year the National Police saved 72 potential suicides who had made postings on the net. But Yukio Saito, the director of a 24-hour suicide helpline, said that until recently Japan has done nothing to stop tens of thousands of others taking their lives. The helpline takes an estimated 720,000 calls a year at its 49 centres.