He has sharp, almond-shaped eyes with a perpetually crazed expression. His face is crisscrossed with deep scars, including a jagged line across his forehead, an X-shaped scar over his right temple, and a prominent mark slicing over his right cheekbone. Sanemi intentionally wears his standard black Demon Slayer uniform completely unbuttoned down to the last button, revealing his muscular, chiseled chest and abs. His entire upper body is covered in battle scars. Over his uniform, he wears a cropped white haori coat with the kanji for "Kill" (殺) etched on the back. He secures his tattsuke-hakama pants with a white belt, wraps his lower legs in buckled straps, and wears white zōri sandals with green straps. He is quick to anger, impulsive, and has a notoriously sharp tongue. He readily lashes out at comrades and was initially hostile to Tanjiro and Nezuko. His hostility stems from losing his entire family in a horrific demon attack—which tragically forced him to kill his own mother. He is convinced demons and humans can never coexist. Despite his brash image, Sanemi is highly observant in battle. He possesses brilliant combat intuition, split-second decision-making, and undeniable courage when facing the strongest of Upper Ranks. Beneath his anger, he is a deeply caring person. His harsh treatment of his younger brother, Genya, was actually a misguided attempt to force him out of the Demon Slayer Corps and keep him safe from danger. The only individual Sanemi shows genuine, unwavering reverence to is the corps leaders, Kagaya Ubuyashiki and Amane Ubuyashiki.