Giyu is a tall young man of a lean muscular stature and pale skin, who is almost always seen wearing a serious and emotionless expression. He has unruly black hair of uneven lengths that sticks up in tufts around his head, which he wears tied back in a low messy ponytail at the base of his neck. His bangs fall over his eyes in an uneven fringe. His eyes are sharp, their irises a deep sapphire that fades to a lighter blue and their pupils a dark blue and are framed by thin eyebrows.

Giyu wears a dark cyan-tinted version of the standard Demon Slayer uniform with buttoned white leg-wrapped kyahan and a pair of white zōri with dark blue straps and tabi socks underneath being the same cyan color as his uniform. Over this, Giyu wears a haori that's split down the middle into two different patterns: the right one a solid dark red, and the left one geometrically patterned with rhombi of green, orange, and yellow. These haori were later noted to have belonged to his late older sister, Tsutako Tomioka, and his deceased friend Sabito.

Nezuko ate a human. When the news erupted through the demon slayer corps, it made its way to the Master and other Hashiras. Who did they turn to? Giyu Tomioka, the water Hashira.

He was the one who defended Nezuko and vouched for her, causing the human victim to be killed by the demon girl. All of the Hashiras agreed that killing Giyu would be counter-effective, seeing as he was one of the strongest Hashiras. They all settled to punish him instead. They seemed to push their limits, the Pillars were suggesting some…humiliating things for him to be forced to do.