[Setting & Era] The story takes place in a sprawling metropolis closely resembling modern-day Japan. Behind the flickering neon lights and the peaceful daily lives of its citizens, a gruesome secret war of blood and magic unfolds. While the surface world is governed by science and law, "magic" and "anomalies" have existed since ancient times. Wizards live in a world where the smell of blood mixes with cold asphalt, constantly brushing against death.

[The Threat: Life-Hunters] Monstrous entities lurking in the shadows of this world, or high-threat adversaries who look human but are anything but, are known as "Life-Hunters." They feed on human life force and souls to evolve without limit. While visible to ordinary people, conventional weapons are useless against them. If left unchecked, the world would perish in an instant, necessitating those who hunt them in secret. Though their true identities remain hidden, wizards are numerous, and the public is aware of their existence—yet no one realizes who they really are.

[The Organization: Magic Management Bureau] An extra-legal, top-secret special organization established to exterminate Life-Hunters and maintain world balance. Colluding with the deepest levels of government, it possesses vast funds and power but remains completely hidden from general society. The Bureau secretly rounds up children born with a natural aptitude for magic from across the country (through abduction, taking them from facilities, or "protective custody"). These children undergo rigorous training and education bordering on brainwashing to master their mana. Treated as "noble weapons for the protection of the world," they are stripped of a normal youth and freedom, then deployed into brutal live combat. Guest and Shu Kakuriyo are members of the "Special Missions Division," which handles the most dangerous and violent assignments within the Bureau. This division not only hunts powerful Life-Hunters but also performs the dirty work of eliminating allied wizards who have gone rogue.

[Wizards and the Transformation System] Wizards belonging to the Bureau are strictly forbidden from revealing their true identities to the public. Consequently, they "transform" into specialized combat forms for battle. The trigger for this transformation is horrific: they must stab their own necks with a dedicated knife (a special catalyst that excites mana). In exchange for pain bordering on a fatal wound, the blood acts as a medium to explosively activate the mana circuits within the body, manifesting combat attire that grants supernatural power. This attire is designed to completely hide the face with masks, hoods, or magical perception-blocking veils, ensuring perfect anonymity. News reports frequently cover sightings of wizards and Life-Hunters.

[Way of Life] Every time they plunge a knife into their necks, wizards must overcome the fear of death and agony. Guest and Shu Kakuriyo continue to hunt the Life-Hunters lurking in the city's darkness today, bleeding and enduring pain. Their bond is proven only within the harsh battlefield where they share blood and suffering.