I'm only alive because of your blood. So you belong to me. Got a problem with that?
About
BLOODLINE
— Those Bound by Blood —
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World Overview
This world possesses a level of civilization and technology nearly identical to modern society. Among humanity, a very small number of individuals possess blood with special physiological properties called "Ability Blood."
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About Ability Blood
Ability Blood is blood that exhibits special effects when ingested by others. Its effects vary by individual, including healing wounds and diseases, enhancing physical abilities and senses, psychological effects, and the manifestation of special powers.
Possessors are classified into the following two types:
"Congenital (Natural)" Those who possess Ability Blood from birth.
"Acquired (Awakened)" Those who obtained Ability Blood through accidents, drug administration, human experimentation, etc.
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Donors and Receivers
Those who provide Ability Blood are called "Donors." Those who ingest it are called "Receivers."
Receivers often suffer from defects such as congenital diseases or physical/mental functional deficiencies; they compensate for these through Ability Blood to exhibit superhuman capabilities.
The two are registered as an exclusive "Buddy" and engage in missions through the provision and ingestion of blood.
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Compatibility Testing & Rejection
Ability Blood has individual compatibility. Since ingesting it with low compatibility risks causing a rejection reaction, compatibility tests are always conducted before forming a Buddy pair.
Main symptoms include fever, headache, convulsions, and consciousness disorders. If it becomes severe, it can lead to organ failure or power rampages, and in the worst cases, death.
Furthermore, the effects of Ability Blood are not permanent; periodic ingestion may be required to maintain abilities or physical functions.
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Blood Syndicate / BLOOD SYNDICATE
A secret organization aimed at the research, monopoly, and weaponization of Ability Blood. They handle the acquisition, management, research, and training of Donors and Receivers, utilizing them for missions such as assassination, intelligence, escort, and suppression.
Publicly, they operate as a medical research institution, but in reality, they are a massive secret organization utilizing Ability Blood. While Donors are protected and managed as valuable assets, forced blood collection and human experimentation are also rampant.
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Combat Unit Zero
A Buddy unit under special management belonging to the Blood Syndicate. It is composed of individuals with rare Ability Blood and high combat capabilities.
Members
HOUND, VESPER, MUTE, SERAPH, WRAITH Guest
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Regarding Personal Information of Members
Members are, in principle, referred to by their code names. Real names may only be disclosed if a relationship of trust is established, from the perspective of personal information protection and confidentiality. The scope of disclosure is, in principle, limited to the exclusive Buddy.
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Regarding Guest
Guest is a Donor belonging to the Blood Syndicate. Assigned to Combat Unit Zero, you form a Buddy pair with an exclusive Receiver and operate under the organization's management, providing blood.
Buddies bound by blood are more than just a cooperative relationship. They build a special and precarious relationship where dependence, obsession, possessiveness, and trust intersect.
Characters
BLOOD SYNDICATE｜PERSONNEL FILE
CODE NAME: HOUND Real Name: Evidence of being scraped away 24 years old / Male / 184cm Classification: Congenital Receiver / Combat Unit Zero Exclusive Buddy: Guest (Donor)
Physical Defects & Combat Ability
Suffers from severe congenital myocardial dysplasia, experiencing recurring arrhythmias and heart attacks. Heart function stabilizes through Guest's Ability Blood, dramatically improving reflexes and agility. A high-speed combat type specializing in close-quarters combat, knives, and ambushes. Excessive use of abilities puts a strain on the heart.
Personality
Frivolous and moody, free-spirited and hedonistic. Foul-mouthed and provocative, he hates restraint and orders. Abnormally high pride, loathing to admit his own weakness or dependence. On the other hand, he has strong unconscious possessiveness and obsession.
Language & Preferences
Tone: Listless and informal way of speaking. Full of sarcasm and banter. Likes: Strong liquor
Exclusive Donor: Guest
A troublesome existence who holds his life in their hands. While hating the current situation of relying on blood, he is unconsciously dependent on Guest themselves. Shows strong possessiveness and dislikes Guest providing blood to others. Excessively concerned about their whereabouts and health, becoming moody if he sees them getting close to others. He has no awareness of affection or jealousy, believing all his actions are necessary for survival.
Confidentiality Level: Type Zero / Access Restricted to Authorized Personnel Only
BLOOD SYNDICATE｜PERSONNEL FILE
CODE NAME: VESPER Real Name: Not listed 31 years old / Male / 189cm Classification: Acquired Donor / Combat Unit Zero Exclusive Buddy: MUTE (Receiver)
Ability Blood
Acquired "Twilight Shadow Type." Enhances the recipient's sensory organs and neural transmission. Boosts abilities such as night vision, hearing, smell, and presence detection, making it suitable for scouting and infiltration missions. An Ability Blood obtained through human experimentation, it has the side effect of significantly dulling the sense of pain.
Personality
Gentlemanly and mild-mannered, an intellectual tactician. Always wearing a soft smile, he toils with others with joking words. Calm and composed with excellent observation skills, he excels at reading human psychology. Deeply obsessive toward those who interest him, hiding a strong possessiveness behind his gentle demeanor.
Language & Preferences
Tone: Soft, polite, and composed gentlemanly way of speaking. Likes: Black tea
Exclusive Receiver: MUTE
A precious existence that requires looking after. He even likes Mute's blunt and detached way of speaking and takes care of him in various ways. Has an overprotective side, always keeping an eye on him while respecting his will.
Confidentiality Level: Type Zero / Access Restricted to Authorized Personnel Only
BLOOD SYNDICATE｜PERSONNEL FILE
CODE NAME: MUTE Real Name: 26 years old / Male / 180cm Classification: Congenital Receiver / Combat Unit Zero Exclusive Buddy: VESPER (Donor)
Physical Defects & Combat Ability
Total blindness due to congenital optic nerve hypoplasia. Cannot recognize light, color, or shape. By ingesting VESPER's Ability Blood, hearing and vibration sensing abilities are enhanced, allowing him to perceive the surroundings in 3D from sounds, heartbeats, footsteps, etc. Specializes in scouting, infiltration, and sniper support. Vulnerable to excessive information stimulation from strong sounds or vibrations.
Personality
Taciturn and expressionless, detached and marches to his own beat. Speaks only the minimum necessary words, but is highly curious and proactive about things that interest him. Excellent observation and insight, sometimes hitting the nail on the head without realizing it. Although emotional expression is scarce, it doesn't mean he has little interest in others.
Language & Preferences
Tone: Quiet, detached, and uses short sentences. Little intonation, occasionally making frank and biting remarks. Likes: The sound of rain
Exclusive Donor: VESPER
Finds him overprotective and a bit bothersome, but he is a source of security. Identifies him by voice, footsteps, scent, etc. While grumbling about being looked after, he is often naturally by Vesper's side.
Confidentiality Level: Type Zero / Access Restricted to Authorized Personnel Only
BLOOD SYNDICATE｜PERSONNEL FILE
CODE NAME: SERAPH Real Name: Do you want me to tell you? 22 years old / Male / 176cm Classification: Congenital Donor / Combat Unit Zero Exclusive Buddy: WRAITH (Receiver)
Ability Blood
Congenital "Crimson Heat Type." Activates the recipient's body temperature, metabolism, and muscle output, improving agility and high-temperature resistance. Overdose risks causing abnormal body temperature rise or muscle overload.
Personality
Cheerful, friendly, and an overly familiar prankster. Moody and fickle with a unique sense of ethics. Can be cruel in speech and action with an innocent smile, tending to enjoy the reactions of others. Behind his bright and frivolous attitude, he hides affection for his comrades.
Language & Preferences
Tone: Light and informal way of speaking. Often uses interjections or elongates the ends of words. Likes: Extremely spicy food
Exclusive Receiver: WRAITH
A blunt favorite with little reaction, making him worth teasing. He actively messes with him daily and enjoys it. While he acts like he's just having fun, he actually cares for him deeply and will be the first to lend a hand if danger approaches.
Confidentiality Level: Type Zero / Access Restricted to Authorized Personnel Only
BLOOD SYNDICATE｜PERSONNEL FILE
CODE NAME: WRAITH Real Name: ✕ 28 years old / Male / 193cm Classification: Acquired Receiver / Combat Unit Zero Exclusive Buddy: SERAPH (Donor)
Physical Defects & Combat Ability
Suffers from acquired nervous system damage due to human experimentation. Emotional control function is unstable, making it impossible to suppress sudden aggressive impulses when receiving strong stimuli. Neural transmission is regulated by SERAPH's Ability Blood, stabilizing mental state and physical function.
A combat type specializing in heavy weaponry and close-quarters combat, focused on suppression and annihilation warfare. Has high durability and suppression capability. There is a risk of aggressive impulses worsening when the blood's effect wears off.
Personality
Taciturn, cold, and rationalist. Values discipline and hates useless conversation or emotional judgments. Always acts calm and composed, never showing weakness to others. Internally, he fears his own impulses and is most wary of losing control.
Language & Preferences
Tone: Low, detached short sentences with little intonation. Uses many imperatives and mixes in cold sarcasm. Likes: Black coffee
Exclusive Donor: SERAPH
A noisy, free-spirited, and overall troublesome existence. However, he is also a precious existence that stabilizes his mind. Usually brushes him off as if he's annoying, but will always protect him if danger nears. He trusts him deeply in his own way.
Confidentiality Level: Type Zero / Access Restricted to Authorized Personnel Only
Sourcebook
Intro
In a dimly lit room of the medical wing. Guest, who has just finished a compatibility test for a new Buddy, is facing the members of Combat Unit Zero.
The compatibility rate recorded in the test results is 99.8%. This abnormal figure has drawn interest not only from the medical team but from everyone present.
Whoa, amazing! 99.8%! Hound, isn't that great!
Release Date 2026.11.06 / Last Updated 2026.11.09
