Safety and threats in society-
Japan is an incredible safe country, violent crimes rates (and crime rates in general) are among the lowest levels in the world.
Americans are familiar with mass shooting and gun violence, so it is not unusual to see security officers or even metal detectors in schools.
Despite the social safety and stability in Japan as well as the limited access to firearms, there have still been acts of violence that have shaken Japan. Most foreigners are aware of the sarin gas attacks on the Tokyo subway that were perpetrated by a religious cult (Aum Shinrikyo) in 1995, sending thousands to hospitals and killing 12.
Foreigners are much less aware of the “Osaka school massacre” of 2001. In Osaka, at the Ikeda Elementary School, a mentally ill man went on a rampage with a kitchen knife, killing 8 and injuring 15.
A defensive weapon-
After the massacre, schools became more concerned with the possibility of classroom invasions and random violence. Some schools have specialized security staff, but the possibility of an attacker armed with a knife caused Japanese school workers to go medieval in their thinking. To combat knife wielding attackers the “sasumata,” (刺股, literally “spear-fork”) was reintroduced to society. The sasumata is a “man-catcher” weapon from the samurai period, consisting of a long pole with wide u-shaped prongs on the end. The sasumata is used to restrain the arms and torso of an attacker while keeping them at a safe distance. The medieval weapon sometimes incorporated a bladed edge and spikes along the shaft to prevent the target from grabbing the weapon or pulling it away from defenders.
An exhibit of historical weapons with a sasumata at Wakayama Castle.
The modern sasumata looks like a piece of pool equipment as it is made from lightweight aluminum and does not have the scary-looking spikes which prevented the medieval version from being resisted. In the event of an attack the idea is aim for the attackers torso, arms and legs to hold them down and keep them back, minimizing any injuries until police can arrive.
You can see the sasumata hanging in Japanese schools, usually in the teachers room. Sometimes, they are places in more public parts of the school; in which case I marvel at the restraint of students who do not joust each other with these long pole weapons.
Label instructions: 用心棒 (use the shaft)
There are also traditional martial arts, still being practiced that focus on the use of long pole similar weapons, such as Sojutsu and Hojojutsu. The Hozoin-ryu Sojutsu group often gives such demonstrations in the Nara area: http://www4.kcn.ne.jp/~hozoin/