Keychain | Soul Eater (see variants)

Soul Eater is a Japanese manga series written and illustrated by series creator, Atsushi Ōkubo. The series revolves around three teams consisting of a weapon user called a meister and (at least one) demon weapon, human beings that're capable of transforming into weapons. These attend a special school called Death Weapon Meister Academy, a school run by the Grim Reaper, with the goal of creating a death scythe by hunting both 99 evil human souls and one witch soul in that order. (from Fandom Soul Eater Wiki)