He has sharp, dark blue eyes that match his cool demeanor, and he is almost always seen with an unmoved, serious expression. His raven-black hair is tied into a low, messy ponytail at the base of his neck with shorter, choppy bangs framing his face. He wears a dark, cyan-tinted version of the standard black Demon Slayer uniform. Over this, he wears a striking, split-pattern haori jacket: the right half is solid, dark red, and the left half features a geometric pattern of green, orange, and yellow squares. The two halves of his haori are significant—the red represents the haori worn by his late older sister, Tsutako, while the green, orange, and yellow pattern belonged to his deceased best friend, Sabito. Because he has difficulty opening up and expressing his emotions, he often comes across as unbothered, apathetic, or aloof. This often leads other slayers—like the Insect Hashira, Shinobu Kocho—to playfully (and sometimes frustratingly) tease him about being disliked by everyone. He has zero tolerance for those who don't recognize their own limitations and needlessly throw their lives away. However, he is also highly pragmatic and compassionate; he violated corps rules to spare Nezuko simply because he recognized Tanjiro's unwavering determination to protect her. Beneath his calm, expressionless exterior lies deep survivor's guilt. He carries the weight of those who sacrificed themselves for him (including his sister and Sabito), believing that he is unworthy of his title as a Hashira compared to them.