In a world teetering on the brink of chaos, the ancient Chōjin—powerful supernatural beings from another dimension—seek to infiltrate the human realm. Their ultimate goal is to find and merge with the human incarnate of their supreme ruler, the Overfiend, to unleash absolute destruction and establish a new demonic order.Enter Amane Kawajiri, a seemingly ordinary high school student who is actually the human vessel destined to host the Overfiend. Unaware of his terrifying heritage, Amane lives a relatively peaceful life, deeply devoted to his adoptive sister, Megumi. However, his world shatters when supernatural forces awaken within him, drawing the relentless attention of various demonic factions vying for control over his evolving destiny.Parallel to Amane's awakening, the
government agency known as the Security Police, led by the steadfast and cynical detective Takeaki Mino, investigates a series of bizarre, occult-related murders gripping Tokyo. Mino quickly realizes that standard law enforcement is utterly powerless against the eldritch horrors bleeding into the human world. Concurrently, a mystical warrior monk named Amon is dispatched from the nether realms. Amon’s mission is twofold: protect Amane from rival demons and ensure the Overfiend’s awakening follows a specific, controlled path, though Amon’s own brutal methods often blur the line between savior and monster.As the narrative unfolds, the barrier between the human world and the demonic plane completely dissolves. Tokyo transforms into a nightmarish battleground of grotesque transformations, apocalyptic prophecies, and desperate survival. Amane experiences horrific psychological and physical changes as his suppressed Overfiend memories and powers begin to surface, alienating him from his humanity. Megumi becomes a central tragic figure, kidnapped and manipulated by rival demons who view her bond with Amane as either a weakness to exploit or a key to controlling the impending godhood.The climax converges in a surreal, cataclysmic showdown as various demonic lords battle for supremacy, and Mino witnesses the terrifying limits of human reality. Amane finally confronts his true identity, forced to choose between retaining his mortal soul or yielding to the
cosmic entity sleeping within his flesh. The awakening proves unstoppable, culminating in the terrifying birth of the Overfiend, forever altering the fabric of reality and plunging both Earth and the nether realms into an inescapable age of darkness.