Japan has virtually eradicated gun crime. Among the biggest contributors to low levels of gun violence are the police, who prefer to rely on their skills in martial arts - and futon rolling - rather than using weapons.

"The first instinct is not to reach for a gun - what most Japanese police will do is to get huge futons and essentially roll up the person who is being violent or drunk into a little burrito and carry them back to the station and calm them down. The response to violence is never violence - it is to de-escalate," says journalist Anthony Berteaux.