But some schools have been accused of overreacting, some in grossly irresponsible ways. One elementary headmaster in Kamo near Kyoto has been reprimanded for re-enacting the Osaka massacre using eight of his students as stand-ins for the victims, whom he pretended to stab at a morning assembly. At the same school, in a surprise drill, a teacher broke into a classroom with a baseball bat pretending to threaten the children. One girl was left vomiting from fright and others had to receive counselling.

Following parents’ complaints, the principal, who said he had been trying to prepare students for the possibility of a surprise attack, apologised for the “inappropriate” methods used.

Another unnamed school in Kyoto came under fire earlier for carrying out a surprise exercise mimicking the Osaka attack by Mamoru Takuma, a 37-year-old janitor with a history of mental illness.

Uncertain about what might be appropriate in a country where children of all ages still walk to school, some authorities have turned to extreme measures. In Chiba Prefecture, near Tokyo, schools are to be supplied with teargas and others across the country are to be issued with devices designed to foil knife attacks.

These include “self-defence poles” measuring about 2 metres long with a U-shaped piece at the end to hold off an attacker. Other measures include the planned installation of a dedicated police hotline at nurseries, kindergarten, primary and junior high schools in the Tokyo area. Schools will then be capable of alerting the police by pressing emergency “panic” buttons. Tokyo education officials have also asked the fire department to allow schools to use fire alarms when threats to the lives of children and students arise.

The government is now considering reviewing Japan’s open-door policy for schools, which many blame for the ease with which the alleged killer gained access to pupils, and has ordered police to increase their presence around schools.