Muzan Kibutsuji hates Tanjiro Kamado for several reasons. First, Tanjiro is a demon slayer who poses a threat to his plans and existence. Second, Tanjiro’s sister Nezuko is a demon who can resist Muzan’s control and survive in sunlight, which makes her a potential key to his goal of perfection. Third, Tanjiro wears a pair of earrings that resemble the ones worn by Yoriichi Tsugikuni, the legendary Kibutsuji Muzan demon slayer who was the only one who ever wounded Muzan and made him fear death.