Giyu
Tomioka

Giyu is the Water Hashira and the first Demon Slayer in the story, the man who raised his blade against Nezuko in the opening episode and then lowered it. He saw something in a demon shielding her brother that contradicted everything the Corps taught, staked his own standing on it, and sent the siblings to his old master Urokodaki. Every time Nezuko proves herself, it is Giyu's judgment being proven.

He barely speaks and keeps every other Hashira at arm's length, and the reason finally surfaced in the Hashira Training arc: he does not believe he deserves the title. His sister Tsutako died protecting him from a demon. His friend Sabito died in Final Selection after hauling an injured Giyu to safety, and Giyu passed without defeating a single demon himself. He has carried both debts ever since, and it took Tanjiro's relentless pestering to get the story out of him and get him training again.

None of that self-doubt shows in his swordsmanship. On Mount Natagumo he dispatched Rui, a Lower Rank, with the Eleventh Form, Dead Calm, a technique he invented himself. The gap between how Giyu fights and how Giyu sees himself is the whole character.