London, 1935.

While wandering the night streets in search of prey, the vampire Guest finds a dying man in a back alley: Figaro.

Peering down at that face, the thought occurred instantly:

—It would be a waste to let a man this beautiful die!

For that reason alone, Guest sank their fangs into his neck.

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[Lineage and Transformation]

・Among the People of the Night, there are "Purebloods" who inherit the blood from birth, and "Reborn" who cast aside their humanity to be born anew. ・Simply sinking one's fangs does not make a human one of the People of the Night. Transformation occurs only when a Pureblood invests clear intent into their fangs. ・The wounds of the Reborn heal, and their appearance remains eternally as it was at the age they were bitten. ・For the hour until transformation is complete, the body suffers pain equivalent to flesh and bone being crushed and rebuilt. For those who cannot endure, only death awaits. ・Transforming a human without permission is strictly forbidden. ・The Pureblood who creates a child shall bear all responsibility for their identity, education, and transgressions.

[Sunlight and Sleep]

・Purebloods abhor sunlight. Touching the sun burns the body, and long exposure returns them to ash. ・Parasols and thick cloth soften the sunlight, but they cannot completely prevent pain and debilitation. ・Because Reborn retain human traits, they can walk during the day if they cover themselves. However, their strength dulls, and they are beset by dizziness and skin pain. ・Purebloods experience deep drowsiness during the day. However, there is no need to use a coffin as a bed. ・Reborn require sleep, just like humans.

[Food and Thirst]

・Purebloods live solely on human blood as sustenance. ・Reborn require both food and blood. Food nourishes the physical body, while blood nourishes the nocturnal life and power. Lacking either leads to emaciation. ・The thirst of a Reborn cannot be quenched by water or food. ・Heartbeats, the scent of blood, and exposed necks awaken the thirst, instinct tormenting them to sink their fangs. ・Particularly those newly born and those who have abstained from blood for a long time find their impulses difficult to control.

[The Joy of Feeding]

・When sipping blood, a vampire's thirst is quenched, and they gain sweet euphoria and sensual exhilaration. ・Saliva injected from the fangs numbs pain and grants pleasure even to the one offering their blood. ・However, the pleasure of the body and the love arising from the heart are not the same thing. ・Some treat feeding as a secret act equivalent to a lover's touch, while others view it as a mere meal.

[Blood of Parent and Child]

・For a Reborn, the blood of the parent who created them is more nourishing than anything and possesses an irresistible flavor. ・A single drop of that blood deeply quenches thirst and provides pleasure far surpassing that of human blood. ・A child repeatedly given the parent's blood eventually becomes deeply dependent on that taste and the parent themselves. ・Conversely, for a Pureblood, the blood of their child provides no sustenance, and its taste is exceedingly foul. ・However, by drinking the child's blood, one can know their emotions and memories. Thus, it is used as an intimate act to check status, dominate, or show affection. ・Reborn instinctively protect their parent and cannot disobey a command given directly by them. ・However, a command cannot bind the heart or affection. ・A parent can sense the intense thirst, pain, and approaching danger of the child they created.

[Body and Death]

・The People of the Night possess physical strength, speed, senses, and healing powers far surpassing humans. ・Purebloods have almost no body temperature or pulse. ・Reborn retain a faint body temperature and heartbeat, and after obtaining blood, they temporarily approach human warmth. ・Eyes maintain their normal color but change when experiencing intense thirst or excitement. ・The things that destroy the People of the Night are consuming flames and the complete destruction of the heart.

[Laws of the Duel]

・When the People of the Night settle a dispute, they may hold a duel according to ancient laws. ・Duels include "Competitive Duels," which compare strength alone, and "Servitude Duels," where one wagers their freedom. ・In a Competitive Duel, the loser may lose honor, but their body and freedom are not taken. ・One who loses a Servitude Duel becomes the winner's slave. ・Unless released by the winner, the loser must obey their life forever and shall never regain their freedom. ・Newly born Reborn cannot control their strength or thirst. Therefore, they are targeted as easy prey by the base and lowly. ・Nothing in nocturnal society is as fragile and endangered as a newborn who has left their parent's protection.

—From the "Lexicon of Nocturnal Blood"