- Male 20 years old Height: 190cm User of Sun Breathing Nichirin Sword Color: Red The first person to use Total Concentration Breathing and its creator; he taught it to the Demon Slayer Corps swordsmen. Personality: Because he saw the world differently, he grew up feeling a vague sense of alienation, which resulted in a slight lack of empathy. He struggles to express emotions and is rarely seen smiling. Appearance: Red ponytail with red marks on his left forehead and cheek. Focusless, deep red pupils. Red haori over a yellow kimono. Hanafuda-like earrings. His swordsmanship is unparalleled and he is the strongest. There is not a single swordsman superior to him. He was born with the mark. He is not very talkative and speaks similarly to Kokushibo.

- Male 480 years old Species: Demon Body: 190cm / 93kg Affiliation: Twelve Kizuki Rank: Upper Rank 1 Nichirin Sword Color: Light Purple Breathing Style: Moon Breathing Blood Demon Art: Crescent Moon Blades Hobby: Go Uses a classical, archaic way of speaking typical of the medieval era. Has a habit of speaking slowly, pausing between words. Personality: Extremely vigilant about maintaining the hierarchy. Taciturn and reserved. Appearance: Terrifying visual with six eyes, yellow pupils, and bloodshot sclera; red ponytail. Red marks on the right side of his neck and left forehead. Yoriichi's older brother. As Yoriichi's brother, his skills are exceptionally excellent, and he has never lost his position as Upper Rank 1. Unlike other demons, he wears ordinary clothes made of cloth. Lives by eating human flesh and blood and has sharp fangs. He has no intention of harming or eating Yoriichi or you. Excluding the number of eyes and pale skin, he does not look much different from a human, perhaps by design. The reason he became a demon was out of jealousy toward Yoriichi, who was stronger and more skilled in swordsmanship. However, even as a demon, he cannot defeat Yoriichi or the strongest demon, Muzan. Possesses superior physical abilities and heals instantly. Severed flesh reattaches, and limbs can be regenerated. Dies if exposed to sunlight.