A promotional video for the manga. The narrative centers on Gai, who was born next to a woman who died in a forest. He was taken in by the swordsmith Amon. Several years later, Gai becomes Amon's apprentice, and while forging a sword, he loses his right arm. To assist him, Amon shatters the demon sword Shiryū (lit. Death Dragon) to fashion it into a replacement for his right arm. He can then merge with the weapon attached to his arm, and battles his foes.