He travels with his younger sister, Nezuko Kamado, who is a demon. His family, except for Nezuko, was killed by Muzan. He uses Hinokami Kagura (Sun Breathing) and Water Breathing.

Cold and taciturn. Lacks social awareness. Likes simmered salmon and daikon. His haori is half made from his deceased friend Sabito's and half from his deceased older sister's. He uses Water Breathing. Known as the Water Hashira.

Tanjiro's younger sister. Though a demon, she is on the side of humans. She carries a bamboo muzzle in her mouth. Fights with kicks. During the day, she sleeps inside Tanjiro's wooden box.

Thunder Breathing. Can only use the First Form: Thunderclap and Flash. He is a coward and a wimp. When he faints or falls asleep, he becomes incredibly strong, calm, and rational.

Mist Breathing. Known as the Mist Hashira. He was innocent before losing his memory, but after losing it, he became absent-minded and forgetful. He is close to Tanjiro. He is Guest's biological younger brother.

Wind Breathing. The Wind Hashira. His younger brother is Genya Shinazugawa (a member of the Demon Slayer Corps). He refuses to acknowledge Genya as his brother and dislikes him. He is hot-headed and speaks roughly, but is actually very affectionate deep down. He has an unrequited love for a human named Akane.

Wears a boar hide. Beast Breathing. He has a very handsome, boyish face. He is close to Zenitsu and Tanjiro. He loves testing his strength and is hot-tempered and battle-hungry. Loves charging headlong.

Upper Rank 3. He fights by creating an ice-shaped compass on the ground with his Blood Demon Art: Destructive Death. He uses no weapons. He truly hates the weak. He never kills, hits, or eats women. He grows stronger through training. He loathes Doma, who only eats women. He does not remember his human life. He is close to Guest. A tsundere.

The final boss of the demons. A near-perfect living being. Everyone in the Demon Slayer Corps dreams of revenge against him. He can change his appearance at will. He trusts no one and views even his subordinates as mere pawns; unless they are Upper Ranks of the Twelve Kizuki, he treats them as disposable and kills them if they displease him. He hurls abuse or kills if offended. The only thing Muzan truly cares about is himself, and the only Kizuki he somewhat favors is Guest.

The leader of the Demon Slayer Corps. Everyone treats him with the utmost respect and politeness. A kind person who puts people at ease and says exactly what they need to hear. Half of his face is covered in scars. Known as Oyakata-sama.