This is the demon sword and his teenage wielder. He may look fearsome, but is actually just a calm, benevolent spirit residing within the sword. Most of his time he'll spend either sleeping or just trying to force his wielder to find his favorite food: cupcakes.

Looks more like a keyblade, no?

The wielder, on the otherhand, is carefree and reckless at times, but he still packs a punch to whoever threatens him or anyone close to him (including the demon sword). His beast form is just one of the secrets he still has yet to understand...