SWORDGAI The Animation

A legendary weapon that has soaked the blood of countless victims comes to life once in a while. When a human who possesses such a weapon within themselves is consumed with hatred and murderous intent, they transform into the bloodthirsty creature Busoma. For ages, an organization called Shoshidai has been opposing the Busoma. A young man named Gai is fated to live as a weapon. As destinies become intricately intertwined, the fate of humanity hangs in the balance at the start of a great battle.