Sword Gai

A woman dies a suspicious death in the forest. Her tragic child, Gai, is adopted by Amon, a master swordsmith. More than ten years later, Gai becomes Amon's apprentice, but loses his right arm in an accident while making a sword. Amon crushes the magical sword "Death Dragon" and rebuilds it as an artificial arm for Gai, but...?
A young boy accepts a cruel fate in a whirlwind of battles. Is it darkness that lies ahead for him, or...?