T?shir? Hitsugaya is very young by Soul Society standards. Born in Rukongai, he became the youngest ever to reach captain rank. Thus, he is called a "boy genius" or a "child prodigy" by many. Hitsugaya is very short and his height is comparable to Rukia Kuchiki's. He also has spiky silver-white hair (which tends to draw attention in the human world) and teal-emerald eyes, which evokes his ability of controlling ice and water. He wears standard captain's clothing, save for a green baldric around his shoulders which holds Hyorinmaru, his zanpakuto.

Hitsugaya is generally mature and serious, in contrast to his free-spirited lieutenant, Rangiku Matsumoto, although he can sometimes be short-tempered and irritable. Despite their personality differences, he and Matsumoto seem to be very close. Hitsugaya is shown to also be easily irked by others goofing off or drawing unneeded attention to themselves, as shown when he led a team of Soul Reapers into Ichigo Kurosaki's school. He hates anything that he deems childish and hates being described as something close to a child, evident in a filler episode when he meets Ichigo's sister, Karin, who pats him over the head further angering him. This is also shown more in the omake chapters, where he is repeatedly mistaken for a child, much to his annoyance. Fitting with the nature of his zanpakuto, Hitsugaya dislikes summer and warm weather in general.