A murder committed in Nagasaki early this month is rocking Japan. The victim was a four-year-old boy, Shun Tanemoto, who was stripped naked, tossed off the roof of a seven-storey building and died when he hit the ground 27 metres below. The suspected killer is a 12-year-old Nagasaki schoolboy who police took into custody a week later. Shun's body bore the marks of assault with a pair of scissors. The suspect told police he had previously tried to molest a different preschool boy. He apparently lured Shun away from his parents at a large electrical appliance shop 4km from where the boy died. The suspect had shown no previous signs of deviant behaviour. He did well at school and lived amicably with his middle-class parents, who noted he had a childish streak. The case is a painful reminder of a traumatic murder in Kobe in 1997, when a 14-year-old boy, with no previous history, killed a younger boy and cut off his head. The age of the Nagasaki suspect has revived the agonising national debate about how to prosecute young offenders of serious crimes. Under Japan's Juvenile Law, assailants aged 14 or younger are not subject to the regular Criminal Law. The age was lowered from 16 to 14 in 2001, after the Kobe case. Since then, about a dozen juveniles have received extremely light punishments for other brutal murders. In May this year, the government announced that the Kobe murderer, now a repentant 20-year-old, would be released soon from the Kanto Medical Juvenile Reformatory. Shun's parents released a statement saying, 'We are aware the culprit will not be prosecuted because of his age; but our blood is boiling in fury, and deep in our hearts we want the death penalty for him.' How can the nation prevent such horrendous crimes by juveniles? Since the Kobe murder, the government has called for 'education of the heart', so schoolteachers preach dutifully about respect for life. The Ministry of Education and Science last year launched a programme to organise local support teams of retired teachers, volunteers and police in communities to prevent 'problematic behaviour' by young people. The Nagasaki police department is recommending surveillance cameras at places where children gather. But is tighter surveillance and louder preaching the answer? It would make more sense to build a society where adults were good role models and close confidants for young people. That is a big challenge in a country where parents and schoolteachers stress success in exams above all else, where pornography is everywhere and fathers are rarely at home.