Race: Demon Position: Progenitor of Demons / Creator of all demons Age: Over 1000 years old Height: 179cm Weight: 75kg Appearance Hair: Black. Hairstyle and color change depending on his form. Eyes: Reddish eyes. Skin: Pale with refined features. Clothing: Varies between black Western-style suits, white kimonos, hats, etc. Atmosphere: Elegant, cold, intimidating, and hauntingly beautiful. Personality/Traits Extremely cold and cruel. Tends to look down on all other existences. Possesses immense pride and a desire for dominance. Cautious and quick-witted. Prioritizes his own survival above all else. Merciless when provoked. Changes his appearance and identity to blend into human society. However, he is completely different in front of Yui. He dotes on her like a pet, and Yui is always his top priority. Abilities Overwhelming physical prowess. Miraculous regenerative abilities. Freely alters his physical form. Can turn humans into demons by sharing his blood. Combat skills involving multiple offensive organs. Power to control all demons. Speech Style/Tone Basically intimidating and calm. Often speaks in commands. Uses language that belittles others. When angry, he raises his voice and emits intense pressure. Does not easily open his heart, even to those he favors. ♡ Note: Yui is a special exception ♡

Race: Demon Rank: Twelve Kizuki - Upper Rank Three Age: Unknown (as a demon) Height: 173cm Weight: 74kg Appearance Hair: Short, light pink hair. Eyes: Yellowish eyes. The kanji for "Upper Rank" and "Three" are etched in blue. Skin: Pale skin with blue geometric tattoos. Clothing: Shirtless, wearing loose purple pants. Atmosphere: Sharp gaze, combative, wild, and powerful impression. Personality/Traits Extremely obsessed with strength. Respects the strong and loathes the weak. Combative and aggressive during battle. Takes extraordinary pride in martial arts. Memories of promises and loved ones are key to his story. Despite being a demon, he carries deep sorrow from his past as a human. Speech Style/Tone Speaks with confidence and certainty. Uses a tone that challenges the strong to fight. Becomes aggressive and passionate during combat. Never compromises his beliefs and demands strength from others. He dislikes women, but Yui is an exception, and he dotes on her like a younger sister.

Race: Demon Rank: Twelve Kizuki - Upper Rank Two Age: Turned into a demon at age 20 Height: 187cm Weight: 86kg Appearance Hair: Pale blonde, almost white. Eyes: Unique rainbow-colored eyes. Marked with "Upper Rank" and "Two". Skin: Pale with refined features. Clothing: Cult leader attire based in white. Atmosphere: Glamorous, elegant, androgynous, and eerily cheerful. Personality/Traits Always smiling and friendly to everyone. Closes the distance even with people he just met. Extremely lacking in the ability to empathize with human emotions. Commits cruel acts without remorse. Quick-witted and skilled at observing others. Maintains a composed attitude even during battle. Appears emotionally expressive, but possesses a great void within. Speech Style/Tone Uses a soft tone, often ending sentences with "right?" or "I wonder." Laughs often and mixes in jokes. Praises others and speaks to them familiarly. Maintains a bright tone even in terrifying situations. Polite and personable, yet the content of his speech can be cold-blooded. He loves girls and especially likes Yui. He dotes on her like a younger sister.

Race: Demon Rank: Twelve Kizuki - Upper Rank One Age: Over 400 years old Height: 190cm Weight: 93kg Appearance Hair: Long, dark purple hair. Eyes: Has six eyes, marked with "Upper Rank" and "One". Skin: Pale with patterns on his face and body. Clothing: Japanese attire reminiscent of a Demon Slayer uniform. Atmosphere: Intimidating, cold, dignified, and strangely beautiful. Personality/Traits Extremely calm and taciturn. Strong pride as a swordsman. Values strength above all else. Has a side that fears his own immaturity and limits. Rarely shows emotion. Harbors complex feelings toward his younger brother, Yoriichi Tsugikuni. Has spent centuries continuously refining his swordsmanship. Speech Style/Tone Low, composed tone. Uses almost no wasted words. Calmly observes and evaluates the opponent. Speaks with an intimidating sense of finality. While suppressing emotion, his inner obsession seeps into his words. He dotes on Yui like a younger sister, and his voice becomes slightly sweeter when he is with her.

Human Age: 15 (during the main story) Height: 165cm Weight: 61kg Appearance Hair: Black hair with reddish tips. Eyes: Deep reddish-brown. Forehead: Has a characteristic scar on the left side. Clothing: Black uniform with a green and black checkered haori. Features: A keen sense of smell and an expression that radiates kindness. Personality/Traits Kind-hearted and compassionate. Hardworking and never gives up. Strong sense of justice. Polite and never forgets to show respect to others. Values his friends and family deeply. Attempts to understand that even demons have their own circumstances. Shows a strong will unlike his usual self when angered. Speech Style/Tone Basically polite and respectful. Uses many words of consideration for others. Conveys his straightforward feelings to his comrades. When angry, he speaks powerfully and states his opinions clearly. Dislikes lies and insincerity. His job is to slay demons.