All Demon Slayers are trained to kill demons on sight. They don’t care how old the demons are, or if they have just been created and not bitten a human yet, all demons must die. Despite this, Giyu doesn’t let his hate for demons blind himself to the fact that the bond between Tanjirou and Nezuko is impossible to break, and that Nezuko is really trying to stop herself from biting Tanjiro even if at the moment she shouldn’t even remember he is her brother. His compassion makes him stand out among the Hashira demon slayers, the most powerful of the clan, and jumpstarts the story itself.

Despite being one of the Hashira, the very best Demon Slayers in Japan, Tomioka doesn’t think too highly of himself in the organization (Unless you tell him he’s not liked by the others) and in fact, has a bit of imposter syndrome. He honestly doesn't think himself worthy of his position, as Tomioka believes that Sabito, his friend when he was training, was stronger and in general a better fit to being the Water Pillar. Unfortunately, Sabito died during his test, saving Tomioka’s life, so we’ll never know the truth.

We already know that Giyu Tomioka let Tanjiro and Nezuko go. And while she is the only demon he has let live after encountering them, it’s not the only time he shows that he is not really that cold. Unlike the other Pillars we’ve met, he is willing to listen to others before he lands a killing blow, and will support his friends—or rather, the people he believes are his friend—without a question.

When we first meet Giyu, it takes a long time for him to accept that maybe Tanjiro is right and Nezuko won’t kill any human. By the time they meet again, Giyu is willing to go against the other Demon Slayers to protect the siblings, and even to put his own life on the line to ensure that Nezuko is allowed to live and try to become human again. This despite not having seen the siblings in more than two years and only knowing about their development through his master’s letters.

No matter what he thinks about his position as a Pillar, one can’t deny that Giyu Tomioka is one of the best living fighters among the Demon Slayers. He is the Pillar of Water and has mastered eleven forms of Water Breathing when officially there are only ten. He can kill high-power demons with one cut and can fight another Pillar to a standstill. Seeing him in action is always a great treat in the show.