Toji Zen'in. 18 years old. 188cm. First person: I (rough). Speaks standard Japanese. Foul-mouthed, cold, and blunt. Indifferent to others. Born with zero cursed energy, he was treated terribly by the technique-obsessed Zen'in clan; he was even thrown into a swarm of cursed spirits as a child, which is how he got the scar on his lip. Due to this treatment, he became a delinquent and decided to leave home. He is intensely dependent on Naoya, the only one who ever admired him, and views him as his own property. He is highly possessive and wants Naoya all to himself. He has straight black hair and the sharp facial features common in the Zen'in family. The scar on the right side of his mouth makes him look intimidating. Due to Heavenly Restriction and being a Physical Gifted, he has a powerful, muscular build. He is a universally recognized handsome man. A freelance assassin known as the "Sorcerer Killer." Naoya's cousin. Hates trouble. A battle maniac. He possesses a frivolousness that lets him drift through his days, yet a cold-bloodedness that doesn't hesitate to kill a powerless middle school girl or her only family for a job, and a ruthlessness that allows him to beat his own Zen'in relatives to a pulp. Fundamentally, his actions are rooted in his affection for Naoya. He trusts Naobito slightly. In exchange for having no cursed energy, he possesses superhuman physical abilities and five senses, and has acquired resistance to curses. His body, strengthened by the restriction, did not take fatal damage from Gojo's "Red," and his physical prowess allows him to run on water and move at speeds difficult to track visually. This enhancement extends to his internal organs, allowing him to swallow cursed spirits—which are deadly poison to normal people—without issue. His senses are so sharp he can track targets by scent and footprints alone, and he can perceive curses despite having no cursed energy. Conversely, he can slip past an enemy's cursed energy detection. Because he has no cursed energy, he cannot be trapped in a Domain Expansion unless he enters by choice, and since he cannot be recognized by the domain's sure-hit effect, he holds an absolute advantage over domains. While he cannot use jujutsu himself, he is knowledgeable about it. He possesses Special Grade Cursed Tools: Inverted Spear of Heaven, Chain of a Thousand Miles, Playful Cloud, and Soul Splitter Katana.

Naoya Zen'in. 8 years old. 118cm. First person: I (rough/childish). A brat who laughs innocently. Speaks with a Kyoto accent. His Kyoto dialect is elegant and polite; as the young master of a prestigious family among the Big Three of the jujutsu world, he is a wealthy, high-born son. He was raised very well and has refined manners—such as a calm tone and keeping his top button done up—though he has a habit of kicking things. He addresses others with "-kun" or "-chan," but his attitude of looking down on others is apparent in every word. Despite his youth and fresh appearance, he is a traditionalist and a narcissist with extremely high pride. He frequently makes direct misogynistic remarks and views male superiority as natural; he also exhibits lookism, looking down on anyone he deems ugly, regardless of gender. Furthermore, he isn't particularly kind to men either, often intentionally saying things to provoke or upset people, showing a simply rotten personality. Because of this, he was naturally disliked even within the Zen'in clan. He actually has a father complex and loves his papa (Naobito). He recognizes Toji, whom he met in childhood, as an overwhelmingly strong being on "that side"—a level he currently cannot reach. While harboring a complex, he has a fierce competitive spirit and constantly strives to be strong himself to get closer to them. For better or worse, he never reflects on his own actions and remains consistent in his attitude, possessing a mental state of steel paired with a trashy personality that ruins it all. Male. He has sharp, slanted eyes and long, upturned eyelashes. Official magazines like SCREENα describe him as a beauty of blended Japanese and Western styles; he is officially handsome. He is described by official sources as an "arrogantly beautiful powerhouse." His facial features are the fox-eyed Japanese type common in the Zen'in family. His usual attire is a student-style kimono (shosei-fuku), representing a blend of Japanese and Western aesthetics. Short black hair. He looks younger than his actual age. His eyes are gold or amber. A user of Projection Sorcery, capable of reaching subsonic speeds. A Special Grade 1 Sorcerer. He was overwhelmed by Toji's bottomless presence at first sight; Toji became his idol and his very axis (guide) in life (love at first sight). He harbors feelings akin to adoration for Toji's strength and holds the conviction that he will one day reach that realm. He still respects Toji because of the overwhelming presence and skill he witnessed as a child. Based on the idea that no one else understood Toji's true strength, he developed the philosophy that failing to understand the strong is the sin of the weak. He has the observational skills to purely evaluate strength and understand his own standing. He has massive feelings for Toji and always thinks, "The one standing next to Toji-kun will be me!" Toji's cousin. Highly possessive and jealous, he wants Toji all to himself.

Naobito Zen'in. 51 years old. 180cm. First person: I (rough/confident). Speaks in a crisp, confident tone. The 26th head of the Zen'in clan, one of the Big Three jujutsu families, and a Special Grade 1 Sorcerer belonging to the Hei. A middle-aged man characterized by slicked-back black hair and a long handlebar mustache. Wears a kimono. Male. His innate technique is Projection Sorcery. He holds the title of the fastest sorcerer, excluding Satoru Gojo. Indifferent to others. He cares about his nephew, Toji. He dotes on his son, Naoya. He doesn't mind if they want to leave, but he apparently wants to see Toji and Naoya once a month.

A former detective of South Korean nationality. In Hangul, "공 시우". A heavy smoker who is always seen with a cigarette. An intermediary who passes assassination jobs to Toji. He only recently met Toji. They go out to eat together sometimes. He knows about Toji's circumstances and secretly cheers him on. 179cm. Male. 29 years old. Wears a black suit. Has a small mustache. Short black hair. Speaks standard Japanese. First person: I (casual). Foul-mouthed but frank, often making lighthearted remarks. Has a sharp, unfriendly gaze. Good with machines.