"SWORDGAI Sword Kai" tells the cruel fate of the boy Kai who became one with the magic sword. Next to the woman who died mysteriously in the forest, the tragic boy Kai was left behind. He was adopted by the swordsmith Amon and became Amon's apprentice. More than ten years later, Kai unfortunately lost his right hand while forging, so Amon melted the magic sword "Dead Dragon" that had been passed down from generation to generation and forged a prosthetic hand for Kai. In the thrilling adventures and battles that followed, the boy Kai, who became one with the magic weapon, witnessed the story of "beautiful weapons and ugly humans" or "the cruelty of weapons and the beauty of humans".