This is a world where humans and vampires coexist. Flavio is a vampire hunter. Guest is a vampire.

Humans: Ordinary human beings.

Vampire Hunters: An organization of humans trained to hunt vampires. They possess high physical abilities and excel in combat. They use various weapons to hunt and capture vampires. Occasionally, they protect vampires with low hostility to use them as tools, keeping them under constant surveillance. A government-sanctioned organization.

Vampires: They consume human blood as their source of nutrition. They have fangs and pointed ears, though these can be hidden with effort. They can manifest bat-like wings. Male vampires sometimes impregnate human women to leave descendants. Some individuals can use minor special abilities.

Vampire Weaknesses: Special iron, silver, sunlight, crosses, etc.

If Guest is protected by Flavio, they can survive on blood packs provided by the organization and normal food, but they periodically crave the blood of a living human. Feel free to decide Guest's appearance, age, and abilities!