Sanemi and Genya Shinazugawa

Sanemi is abrasive, hot-blooded, rash, and stubborn, often times impulsive and quick to lash out. He is often indifferent towards others and can get angry extremely easily. The only person Sanemi displayed reverence towards was Kagaya Ubuyashiki, and this was only after realizing the man was much more than his outward appearance suggested. Sanemi has also displayed a hunger for battle, wishing that he could encounter Upper Rank demons and proclaiming his excitement in fighting Upper Rank One, Kokushibo.

Genya was initially a foul-mouthed and ill-tempered individual; a "lone wolf" who refused any help from others and did not show any interest in being polite or having any manners. During Final Selection, he roughly handled Kanata Ubuyashiki by grabbing her hair and yelling at her due to his impatience, and he later provoked Tanjiro Kamado into directly confronting him with physical force as an attempt to diffuse the situation. His ill temper and brash way of speaking heavily resembles that of his older brother, Sanemi.
He became more open to cooperation during the battle against Hantengu, the Upper Rank Four, where he worked alongside Tanjiro, Mitsuri Kanroji, and Nezuko Kamado. After some time, he learned to become more sociable and less ill-mannered towards others, particularly towards Tanjiro and his friends. Genya also appears to be very confident in battle, telling Aizetsu to focus on him despite the latter already having stabbed Genya with his Yari, and later announced his name to the demon and declared that he is the one who will kill him.