Soul Eater is a Japanese manga written by Atsushi Ohkubo and published by Square Enix.

Plot
In a world where evil is rampant, leading to mad men, there is a school in the fictional town located in Death City, Death Valley, Nevada, which trains young boys and girls around the world to fight against the enemies of humanity. The boys are the "Masters of weapons", which aims to raise ninety-nine evil souls and soul of a witch, as to feed their teammates or those who have the power to transform into "Weapons".
In fact the founder of Shibusen or the Shinigami Buki shokunin Senmon Gakk? ("School of specialization for teachers and weapons of the Shinigami"), called in the Italian version of the manga DWMA, that's Death Weapon Meister Academy, is none other than the god of death, which also fulfills the function of principal.
The ultimate goal of school is to maintain peace through the physical elimination of people who delve into the darkness or intentionally committing heinous crimes to humanity, and prevent a new kishin arises. The kishin is a being who fed on human souls innocent and has reached a stage demonic formerly a fencing master called Ashura became kishin doing nearly plunged the world into chaos. The Shinigami defeated him in battle, scuoiandolo and trapping him in a sack made from his skin, where it lies dormant, then imprisoning him in a subterranean city where the DWMA. The evil souls that have to eat weapons are considered "eggs of Kishin".
The teachers follow lectures in various fields from older masters and experts, and follow missions desired by the principal lessons that are called recovery, most of which is to collect souls depraved. Usually the teachers acting alone, with their weapons, but it can happen that you put together with their companions to accomplish their missions.