At times, a weapon that soaked in the blood of thousands of humans become legend and come to life. This story focuses on "Shoshidai" an organization that has been facing "Busouma"s for a long period and "Gai" a young man who is fated to live as a weapon. When a man who possess such a weapon within himself is swallowed in hatred and grow murderous intent, turns into Busouma, a creature that only seek to slaughter...

"SWORDGAI The Animation" is an antihero, action anime that is based on "SWORDGAI" (Character design: Keita Amemiya / Author: Toshiki Inoue / Drawing: Wosamu Kine / Its sequel "SWORDGAI Evolve" currently ongoing), a manga serialized from Nov 2012 in "Monthly Comic Magazine HERO'S".