Blood is the fundamental "mana" of this universe. Its properties change depending on who—or what—is consuming it.
Fuel for Regeneration: For Devils, Fiends, and Hybrids, consuming blood is the only way to heal from catastrophic injuries. A Hybrid can be reduced to a pile of organs, but if enough blood is poured over them, they can fully reconstruct their human form in seconds.
The "Power" Limit: Fiends have a lower "blood capacity" than pure Devils. If a Fiend consumes too much blood, their supernatural traits (like horns or growths) can become enlarged and unstable, forcing them to expend energy to return to a manageable state.
Human Sacrifice: Humans cannot use blood to heal themselves; instead, they use their own blood as a "down payment" for Devil Contracts, often offering liters of it or specific internal organs to manifest a Devil's power for a single strike.
Hybrids are the only entities that possess a mechanical-biological interface. This is known as the Activation Trigger.
Placement: The trigger is always located on a fixed point of the human body (chest, neck, or hand).
The Ignition: Pulling the trigger acts as a literal "start" for the Devil's engine. It forces the human's blood to flash-mutate into high-density weaponry—chainsaws, bombs, or blades.
Post-Transformation: Once the trigger is pulled, the human consciousness remains, but the body enters a state of high-caloric burn. If the Hybrid runs out of blood during a fight, their weaponized limbs will stall or "jam," leaving them vulnerable.
Hell is a physical dimension that exists parallel to the human world. It is not a place of fire and brimstone, but a surreal, infinite landscape.
The Endless Ceiling: The sky in Hell is composed of millions of doors. Each door represents a portal to the human world, through which Devils manifest when they "die" in Hell.
The Grassland: The floor is often depicted as a vast, emerald-green meadow that stretches to a horizon filled with disjointed architectural ruins and the colossal, unmoving forms of Primal Devils.
The Sound of the Engine: It is rumored that the only thing Devils in Hell remember before being reborn on Earth is the sound of a revving chainsaw engine, marking the Chainsaw Devil as the "Hero of Hell."