Anti-Sensei Weapons

The Anti-Sensei Weapons are special weaponry developed for the assassination of Korosensei.

Overview
Anti-Sensei weapons are made with special materials that are only effective against Korosensei and anything composed of the anti-matter tentacles, thus making them harmless to humans. They have been shown in the form of bullets, grenades, knives, nets, cages, and clothing.

Anti-Sensei Bullets
The Anti-Sensei bullets take the shape of BB gun pellets and are used with have been referred to as airguns which take the appearances of real guns. They break apart Korosensei's cells and are able to be used and conformed in a variety of ways from being able to embed them in something to grounding them up into fine powder. These pellets were once used to make a fragmentation grenade by Terasaka in his first attempt to kill Korosensei.

Anti-Sensei Knives
Green knives that have the strength of ordinary rubber. Like the bullets, these are harmless to humans but lethal to Korosensei. They can also be used in a variety of ways: (i.e. cutting them up and pasting them to something) Some of the students wield these knives; Karma owns an Anti-Sensei butterfly knife and Hinata wraps the knife on her ankle. Kayano uses an anti-sensei knife to confront the transformed Reaper and Nagisa uses an anti-sensei knife to kill Korosensei at the climax of the series.

Spear of Heaven
A colossal Anti-Sensei satellite weapon dubbed the "Spear of Heaven". This special weapon works by shooting a silent beam of light specifically designed to vaporize tentacle-based creatures, specifically Korosensei. At full power, the laser can cover the entire zenith of the old campus hill.

Shield of Earth
A large energy dome designed to destroy anything made of the antimatter tentacles, used to prevent Korosensei from escaping the range of the Spear of Heaven. The Reaper, augmented with the tentacles, was killed when he was sent into the barrier. Yanagisawa, also augmented with tentacles, was rendered permanently disabled after being propelled toward the barrier.

Miscellaneous
The materials used to make the Anti-Sensei weapons have also been used to make cloth, clothing, and traps such as:
 * Shiro's robes
 * A cage made by the Reaper

Trivia

 * The air guns used for the anti-sensei bullets are modeled after M4 Assault Rifles and M1911 Handguns.
 * The sniper rifle variant used by Chiba in the anime is modeled after the R93 Sniper Rifle.
 * In the anime, the BB pellets, airguns, and knives have the acronym S.A.A.U.S.O. (Special Arms Against Unidentified Slimy Octopus) imprinted on them.