Isshin is a tall, muscular built man with spiky black hair and brown eyes. He has thin facial hair around his mouth and on his cheeks. As a doctor, Isshin is usually seen wearing a white lab coat over a shirt and trousers. As a Shinigami, he wears the standard Shinigami shihakusho, along with a tattered Captain's haori, worn like a sash and fastened over his left shoulder. The Division insignia cannot be seen as the haori is worn presently.
Isshin typically acts in a goofy, energetic, and fun-loving manner. Loud voice, big smile and a wide range of facial expressions are his trademark features. He's prone to attack his son all of a sudden for every reason, from being late for a dinner to simply waking him up. Like he claims, it was all to make Ichigo stronger, which actually paid off. Sometimes Isshin can be the life and the soul of the party as shown during the festival in Karakura Town. Initially starting the fun with his daughters he finally took almost all of Ichigo's friends with him. As a Shinigami, Isshin is much more serious and focused, but is still prone to arguing, especially with his son.
Master Swordsman Specialist: Despite being rusty, Isshin still possesses great skill in swordsmanship, allowing him to effortlessly slice through Grand Fisher's body and his Zanpakutō with a single swing of his sealed sword. While fighting against Aizen, Isshin used kendō, which he performed very proficiently, breaking concrete into pieces with a single strike.
- Agitowari (Jaw-Cutting): A single sword attack which cuts an opponent in half from the jaw down the length of the body until the target is bisected.
Hakuda Expert: As shown from his repeated attacks on his son, Isshin is a very skilled fighter even when barehanded.
- Isshin Flying Double Knee: A flying double knee attack performed by Isshin against his son as part of their usual playful fighting.
- Isshin Handstand Dash: A simple running handstand used to show his physical capability to his daughters while walking up a hill.
- Chohigezutsuki: A headbutt attack with enough force to send an opponent flying backward a considerable distance.
- Oni Dekopin: A simple finger flick with enough physical force to send an opponent flying a considerable distance away and through multiple physical constructs.
Shunpo Expert: Isshin possesses skill in the use of Shunpo. He can also keep highly fast opponents on their toes from his continuous assaults. He evaded a powerful, point-blank Hadō No. 63. Raikōhō fired by Aizen.
Kidō Master: Isshin is capable of creating charmed objects to act as a defense against hostile forces, such as the Arrancar Grand Fisher. He is also able to erect powerful barriers capable of erasing traces of Reiatsu altogether.
Expert Healer: Isshin is a skilled healer and doctor, as he noted that during his education in the Shinigami Academy, medicine was the only lecture he paid attention to. Coupled with Urahara's assistance, Isshin was able to open a private clinic. Isshin can handle anything short of major surgeries.
Enhanced Durability: Even without his Soul Reaper powers, Isshin can take severe physical punishment (e.g. fighting with Ichigo and being kicked by Karin).
Spiritual Awareness: As a spiritual being, Isshin is spiritually aware. He sensed Grand Fisher from a significant distance.
Immense Spiritual Power: As a former captain and head of one of the Five Noble Houses, Isshin possesses a considerable amount of spiritual energy, but he used to have a greater amount of it before losing his powers. Ichigo and Shinji are able to sense its strong presence from miles away, almost making it unregonisable. Kon was stunned by the level of Isshin's power when he watched Isshin kill Grand Fisher with one swing of his sealed Zanpakutō. Using his Reiatsu, he can fixate the Kōryū in the Dangai by himself for up to two thousand hours (roughly three months) before it runs out, something which lower-echelon Shinigami come in by the dozens to do under normal circumstances.
Engetsu (Scathing Moon): Engetsu's sealed form is that of a normal katana. It has a red handle and sheath, and a hexagonal shaped hand-guard. It is carried from a string wrapped around his belt in an iaido style, and worn with the edge down like a tachi instead of the edge up like a katana. The end of the hilt has a blue tassel.
- Shikai: It's Shikai release command is "Burn". The sword does not change shape upon release, but its blade is sheathed in a form of spiritual energy, which engulfs the sword's tassels, creating long, trailing streams.
- Energy Technique: Isshin can take his blood and spit it onto his sword, doing so activates a large wave of deadly spiritual energy to emanate from the sword and take out his opponent.
- Getsuga Tenshō (Moon Fang Heaven-Piercer): During his battle with Aizen in the Fake Karakura Town, Isshin uses Getsuga Tenshō by gathering immense spiritual energy in his Zanpakuto's blade and slashing down his opponent. When used against Aizen, Isshin's blast was able to demolish a large radius of the fake Karakura Town and leave behind a huge crater.
- Masaki Kurosaki (Wife, deceased)
- Ichigo Kurosaki (Son and rival)
- Karin Kurosaki and Yuzu Kurosaki (Twin Daughters)
- Ryuken Ishida (Best friend)
- Kisuke Urahara
- Yoruichi Shihōin
- Rangiku Matsumoto (Former Lieutenant)
- Tōshirō Hitsugaya (Former Third Seated Officer)
- Minato Namikaze
- Naruto Uzumaki
- Ichigo Kurosaki (Rival, also son)
- Ryuha Armament Alliance
- Sōsuke Aizen (Arch-enemy)
- Grand Fisher
- The Arrancars
- The Espada