Tanjiro is a young man of average height with lightly tanned skin and an athletic, muscular build. His hair is ruffled and black with red tips (appearing black that turns to burgundy at the tips in the anime), and is swept back to reveal his forehead. His eyes are wide and dark red, fading into a burgundy hue with white pupils that appear lighter toward the lower section of the iris, while the upper portion is markedly darker. He bears a distinct scar on the upper left of his forehead - Tanjiro wears the standard Demon Slayer uniform that is similar to the Japanese military uniforms of the Taishō era. His uniform is black in the manga and tinted a mahogany hue, a reddish-brown color tone, in the anime. It consists of a button-up jacket with a stand-up collar and long sleeves, featuring silver buttons and a shirt pocket on the left breast, with the kanji for Destroy (滅めつ, Metsu?) engraved on the back of the uniform. Beneath the jacket, he wears a white long-sleeved collared undershirt. The uniform also includes tattsuke-hakama pants tucked, fastened with a white belt around his waist, and strapped securely around his calves with a pair of buttoned white kyahan, along with tabi socks that match the color of his uniform. On his feet, he wears a pair of white zōri sandals with dark red straps. Over this, he dons his signature checkered haori. He carries a large wooden box on his back (which was a gift to him from Sakonji Urokodaki), where his sister sleeps as they travel through the day.

She is known for her pink eyes, black hair with reddish tips, and the bamboo muzzle she wears to prevent biting. — She can change her size, growing to an adult-like form with vine-like patterns on her skin and a horn when in a more powerful state. She is Tanjiros sister.

A muscular young man with a surprisingly feminine face, often seen wearing a boar's head mask. — Short-tempered, proud, and constantly seeking challenges, but fiercely loyal to his friends.

Bright yellow hair (originally black, turned yellow after being struck by lightning), yellow eyes, and a yellow-and-orange gradient haori over a dark brown Demon Slayer uniform. — Initially appears as a crybaby and womanizer, but this masks a deep-seated fear of death and a strong desire to protect his friends, especially Nezuko.