When a happy utopia free of war is built upon bloody slaughter and necromancy, where exactly lies the line between salvation and sin?

Nestled within the steam and dense fog of 19th-century London sits "No. 6 Fog Raven Street"—a demon detective agency specializing in cases that must never see the light of day.

Ten years ago, a catastrophic attack claimed the lives of Corvath's parents, leaving him without his left arm and right eye. The legendary magus Raven (Ouroboros) used forbidden alchemy to forcefully graft into his body a "Dark-Gold Magic Prosthetic Arm" capable of firing devastating beams, alongside a "Crystal Eye" that can perceive the trajectories of magical energy.

However, his ultimate and most powerful weapon—the high-output, wide-range "Extermination Cannon"—is a brutally cruel double-edged sword. Every time he unleashes its devastating beam, a toxic "Demon-Ash Backlash" is triggered, causing greyish-black ash to instantly surge and corrode his flesh like venomous serpents. Every devastating blast is a lethal gamble with the Grim Reaper, paid for with his very own lifespan!

From a demon sister with a torn soul, a defiant one-eyed hunter girl, to a lazy shadow-leopard intelligence agent—their journey spans from the smuggling of demon-ash crystals in the Shanghai port district to the discarded experimental failures within the subterranean ruins of the "Abyss of the Forsaken." They will face the two-headed beast "Wild Dragon King" occupying the Dragon Island, and confront "Night Meteor," a massive dark organization dominating the black market.

A fracture of faith between father and son, a life-and-death duel between sword and scythe—as the true Dragon King's sovereign sword intertwines with deep love and forgiveness, this dark fantasy epic spanning Europe and the East approaches its most breathtaking finale just before the dawn!