It's been almost two decades since the fall of Nobunaga at the hands of Samanosuke, and the fallen ruler's own vassal Hideyoshi Toyotomi has finally united Japan under the banner of peace... that is, until one fateful June evening when a strange glowing planet appears in sky. From that moment on, Hideyoshi becomes a power-mad dictator and earthquakes, volcanoes start destroying the land. Soon afterwards, the evil Genma begin to reappear, disorder spreads across the country, people are lost, and villages are burned to the ground. But just when it seems that we're approaching Japan's darkest hour, a mysterious warrior with plenty of power appears on the scene to stop it. He's Soki, Oni of the Ash -- otherwise known as "The Blue Demon".