Hisagi is an extremely mature and calm individual, a state that is slightly at odds with his somewhat punk-like appearance. He usually takes responsibility and tends to avoid violence when possible. He seems to be virtuous, much like his captain's image; their views often coincide until it is revealed that Kaname Tosen is a subordinate of Aizen.
He is often in the company of the 3rd Division lieutenant, Izuru Kira, and frequently hangs out with 6th Division Lieutenant Renji Abarai as well. He comes from the lower class, but when he is pressed for cash, he is ready to rely on any free food source available.
Hisagi has stated that he does not like the shape of his Zanpakutō's Shikai release, as it looks like something meant to "reap life itself". He also fears his sword's power, because to him, it is something of a sign of respect to battle for justice as well as a testament to the true strength of one's character. This philosophy is taught to him by his former captain, given the latter's "follow the path with the least bloodshed" creed, indicating a reasonable closeness between the two. It also seems that while battling, he becomes a darker person and seeks to instill fear in his enemies while in battle.
Shuhei Hisagi is a tall and lean-built man with dark grey eyes, short black hair and three scars straight over his right eye that lead down his cheek (gained during a past Hollow attack).
Additionally, he has the number "69" tattooed on his left cheek (inspired by Kensei Muguruma, who saved him from a Hollow when he was young), as well as a blue-striped tattoo running across his left cheek and over the bridge of his nose. He wears a choker around his throat and matching armbands on both upper arms. These have explosive properties which he exploited in his fight with Findorr Calius. Hisagi wears a sleeveless shihakushō, and has his lieutenant insignia tied to his left arm. Back when he asked Tōsen to remove him as a seated officer, he wore a Shinigami robe with sleeves and did not have the blue-striped tattoo. During his academy days, Hisagi's hair was much longer, hanging down to his neck in the back and approaching his chin in the front.
Seventeen months after Aizen's defeat, Hisagi has changed his hairstyle, letting it fall against his face and coming down near his ears..