Soul Eater

Story :  Maka is a scythe meister, working to perfect one particular scythe
until it is good enough to become Death's Weapon -- the weapon used by
Shinigami-sama, the spirit of Death himself. As if that wasn't unusual
enough, her scythe is a demon scythe called Soul Eater, which can
change form from a scythe to a human-looking boy. In order to make Soul
Eater powerful enough to be Death's Weapon, he must eat the souls of 99
humans and 1 witch. Along the way, the two of them face many different
challenges, including a cat witch named Blair (who happens to have a
thing for Soul) and a teacher who's been turned into a zombie (and
wants him to join her!). Her fellow students, like the shadow ninja
weapon meister named Black Star who always needs to be the center of
attention, aren't much help, either. It'll be a miracle if Maka even
survives, let alone manages to make Soul Eater into the Death Scythe.