Once upon a time in feudal Japan there lived a wicked summoner named Seimei who brought a great evil into the world. Only one man could stop him: an adviser to the former chancellor named Tengan. But Seimei anticipated this challenge and had Tengan condemned to prison forever. With no other recourse in sight, Tengan elected to free a sleeping Sumioni, or Inkdemon, named “Agura” at the cost of his own life, bequeathing this creature a compulsory mission through the scorched ruins of Japan to defeat Seimei and wrench order from chaos.