Shūhei Hisagi is a tall and lean-built man with dark grey eyes, short black hair that falls against his face and coming down near his ears, and three scars straight over his eye that lead down to his right cheek (gained in the past during a 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 down across his left cheek and the bridge of his nose. He wears a choker around his throat and matching armbands on both upperarms. These have explosive properties in them. Hisagi wears a sleeveless shihakusho, and has the lieutenant insignia tied to his left arm.
Hisagi is an extremely mature, stern 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 Tōsen is a subordinate of Sōsuke Aizen. After Tōsen betrays the Soul Society with Aizen and Ichimaru, Hisagi forms a friendship with Tōsen's former friend, Captain Sajin Komamura, with both of them resolving to open Tosen's eyes to the truth. He is often seen in the company of 3rd Division Lieutenant, Izuru Kira, and frequently hangs out with 6th Division Lieutenant Renji Abarai and 10th Division 3rd Seat Karin Kurosaki 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, including one provided by someone as obtuse and snotty as 2nd Division lieutenant, Marechiyo Ōmaeda.
Hisagi has stated that he does not like the shape of his Zanpakutō's Shikai, or Bankai 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.
In the absence of Tosen, not only does the leadership of his squad weigh on him, but also the chief editorial position of Seireitei Communication. In what little free time he has, he likes to practice on a guitar that he found on one of his missions to the Human World and brought back to Soul Society. As members of his division find his practice annoying, he tends to do it in the mountains of Rukongai. He receives proper guidance at last in the handling of the instrument from Yasutora Sado after the Ryoka invasion. He dreams of starting a band. He ran a serial article in Seireitei Communication, titled "Please Teach Me! Shūhei Sensei!!", but it never managed to get popular, and was cancelled after having published three lessons on Soul Reapers and the Soul Society. He is also the author of This Hand, That Hand, The Hand Over There and Goodbye To Yesterday's Me. It is also known that he cooks well and his favorite food is Vienna sausage, while he dislikes sea urchins.
Expert Swordsman Specialist: Reluctant to use his Zanpakutō's Shikai or Bankai forms, Hisagi has trained to become especially skilled at swordsmanship so he wouldn't have to rely on both. He has shown to be very crafty with his Zanpakutō as his skills are great enough to regularly fight opponents who released their Zanpakutō while his remains sealed, only relying on his own Zanpakutō's released forms as a last resort.
- Kusarigamajutsu Master: While afraid of his Zanpakutō's Shikai, Hisagi has shown to be highly proficient in its use, using his mastery of a variation of Kusarigamajutsu (which features fighting at a distance with substantial usage of the chains to ensnare opponents, as well as using his Zanpakutō as a long-ranged, throwing weapon). This allows Hisagi to fight using a large variety of attack angles and styles.
Shunpo Expert: Hisagi is proficient enough in Shunpo to keep up with lieutenant-level Shinigami, and even at certain ocassions, captain-level Shinigami. His skill allows him to move fast enough to dodge a vast majority of multiple Bala blasts that are fired at him.
Hakuda Expert: Hisagi has also shown himself to be a highly proficient fighter even when unarmed. During the Bount Invasion, Hisagi demonstrated great skill by incapacitating several possessed Shinigami. In battle, he has shown himself to be tremendously agile and is able to attack from various angles with great dexterity, combining that with his swordsmanship makes him quite versatile.
Enhanced Strength: Hisagi possesses a considerable amount of strength. He easily lifted and slammed the giant Ayon into the ground with his Shikai. He even sent Kazeshini crashing through a nearby wall with a single elbow strike.
Enhanced Endurance: Hisagi possesses a high level of resilience and stamina, evidenced by his ability to take heavy damage from Ayon, and be able to fight and ultimately defeat his former captain, despite receiving further grievous injuries.
Great Spiritual Power: Being a lieutenant of the Gotei 13, Shuhei boasts a high level of spiritual energy. Upon gaining Bankai, this power increases on a scale of 5-10, which makes him a captain-class Shinigami (despite his rank as a lieutenant). His Reiatsu is green.
- Shikai: Kazeshini's Shikai command is "Reap". When released, it takes the form of two Kusarigama-like weapons, each with two scythe blades, with one inverted, giving it the resemblance of a pinwheel. The blades are connected to a spiked rod tethered together by a long chain. While in Shikai form, Kazeshini can be swung by its chains in large circles, allowing the bladed portion to spin like a fan. The chains are extendible, giving Hisagi great ranged ability. Kazeshini can also be used for entangling an opponent's sword, or other weapons; It can even immobilize opponents. Although he dislikes the shape of his weapon, he is extremely proficient in wielding them; he uses them as projectiles and controls them at range by moving its chains, making Kazeshini's paths unpredictable.
- Kubikake (Neck-Hanging): A physical technique that Hisagi can use by throwing the chain of Kazeshini around the neck of his opponent, from here he can pull the chain hanging the opponent strangling or ensnare them knocking them off balance and bringing them toward him.
- Bankai: Fukisarashi Kazeshini (Jagged Demon Wind to Death): When his Bankai is activated, Hisagi's Shikai form of the dual Kusarigama-like weapons transforms into a single, large black scythe with a jagged upper blade and a sharpened bottom end. The scythe has no hilt, but from the base to the handle section, it has dark-grey cloths wrappings around it, and at the hilt's base, it has a long black chain that can be used the same way his Shikai was used in.
- Bankai Special Ability: The Scythe form of Hisagi's Bankai carries the same aspects as his Shikai, but has two new techniques:
- Kurikaze (Neck-Killing):
- Izuru Kira (Best friend, childhood classmate, and partner-in-combat)
- Sajin Komamura
- Kensei Muguruma (Captain)
- Mashiro Kuna (Co-lieutenant)
- Momo Hinamori (Childhood Classmate)
- Renji Abarai (Close friend and childhood classmate)
- Tetsuzaemon Iba
- Ichigo Kurosaki
- Rukia Kuchiki
- Karin Kurosaki
- Orihime Inoue
- Rangiku Matsumoto (Love interest)
- Tōshirō Hitsugaya
- Kaname Tōsen (Former Captain)
- Ryuha Armament Alliance
- Sōsuke Aizen
- Kaname Tōsen (formerly)
- The Arrancars
- The Espada
- The Bounts