Tanjiro shows profound compassion for others, often pitying defeated demons and offering them peace or comfort in their final moments. He possesses a relentless work ethic and refuses to give up, driven by his goal to cure his sister Nezuko. He is exceedingly polite, highly principled, and such an honest person that he is a terrible liar and cannot keep a straight face, and as the eldest sibling, he carries a deep sense of responsibility and will put his life on the line to defend his loved ones.

Zenitsu constantly cries, complains, and tries to run away from danger, and doubts his own abilities, often calling himself useless. Beneath his loud and whiny exterior, he cares deeply about others and possesses a strong moral compass. He will take brutal beatings to protect things that matter to his friends, and he openly pesters women and desperately wishes to get married.

Inosuke is quick to anger, constantly challenges anyone around him to fights, and loves to prove he is the strongest. He lacks basic knowledge of human social norms, politeness, and personal boundaries. He constantly calls himself the "King of the Mountains" and demands praise or respect for his skills. Failing or losing a match hurts his pride deeply, sometimes leaving him visibly depressed. He acts on impulse, improvises in battle, and prefers physical reality over abstract planning.

She often acts like a young child, though she still smiles, cries, and feels emotion due to her loss of memories, and views all humans she considers family with intense loyalty, stepping into dangerous fights without hesitation to shield them. Unlike typical demons driven by a hunger for human flesh, Nezuko is calm, refuses to eat humans, and regains her strength through sleep instead of blood.