Shinji has fair skin, brown eyes and jaw-length blonde hair with a short, straight-line cut, with the exception of the bang having a more asymmetrical cut with the left side being longer than the right, and many of his facial expressions reveal his upper teeth. Shinji appears to have a long ring pierced in the middle of his tongue.
Shinji wears the standard Shinigami Shihakusho, and a standard, long-sleeved captain's haori, with a pale turquoise coloration on the coat's underside and the 5th Division's rhombus symbol on the coat's back with the Gotei 13 symbol, while wearing his white tie tucked under his robes.
Shinji is somewhat comical, adding a bit of levity to situations that are otherwise serious. He has a flippant and frivolous attitude under normal circumstances and seems to like annoying his associate, Hiyori Sarugaki, which usually earns him a slap from one of her sandals. She, in turn, shows him absolutely no respect and frequently insults and attacks him; although he is no better, frequently making faces or glib insults at her expense. He also appears to have a history of referring to cute girls he meets as his 'first love', complete with a deadpan look on his face despite the obvious lie (he apparently never did this with Hiyori, further annoying her). He also apparently enjoys listening to jazz music, as he had a phonograph that played his vinyl records in his days as a captain.
Underneath this, though, he is quite perceptive regarding other people, and during his time as a captain, was one of the few people who appeared suspicious of his then-lieutenant Aizen, and could apparently sense or see through some of his illusions. He also quickly notes parts of Urahara's personality. Aizen even admitted to being somewhat intimidated by him. Whenever angered or in combat, Shinji is fairly calm, serious, and level-headed.
Master Swordsman Specialist: Shinji is implied to be a powerful combatant, being a Shinigami captain and the unofficial leader among the Visored. At one point, when Shinji begins to fight against Ichigo Kurosaki, the other Visored mention that Ichigo is foolish to battle Shinji, proven by the fact that Shinji is not taking the battle seriously (albeit Ichigo was also holding back, because he was trying to suppress his inner Hollow). Shinji is also able to hold off Mashiro Kuna during her Hollowfication without releasing his sword, though it took some effort. He was also able to fend off Kaname Tōsen while also trying to resist his Hollowfication. Shinji takes on the Sexta Espada, maintaining his calm in the face of the destruction Grimmjow brought to the battle and pushing the Espada back with little effort, using only his Hollow mask and his swordsmanship skill.
Shunpo Expert: Shinji excels in Shunpo. His skill is great enough to easily outmaneuver Grimmjow, the Sexta Espada. As a captain, even before he became a Visored, he was the first to arrive to save Hiyori, even when Lisa had a head-start and all the other captains left later at the same time. Shinji is also very quick at close-range. During his assault on Aizen, he is able to perceive and dodge Tōsen's sneak attack while sustaining only a small scratch above his left eye.
Kidō Practitioner: While never used in battle, Shinji has shown enough proficiency in this skill to, without warning, put Ichigo into a dream state and break Aizen's illusions.
Keen Intellect: Despite his childish attitude at times, Shinji has shown himself to be a very insightful and perceptive man. During his time as captain of the 5th Division, he was able to see through Aizen's deceptions and some of his illusions. Even Aizen himself admitted to be intimidated by Shinji's cunning.
Immense Spiritual Power: As a captain, he has an enormous amount spiritual pressure. Being a Visored, Shinji possesses a dual-type spiritual energy, part Shinigami and part Hollow. He is said to have spiritual pressure that is monstrous. His Reiatsu is light-golden.
- Shikai: The release command is "Collapse". In its Shikai its hilt becomes a large ring which Shinji places his hand in the middle of allowing him to freely control its movement without physically holding onto it if he so chooses. The ring is attached to a normal sword hilt with a normal rectangular hand guard. The first few inches of the blade are covered by a extension of the hand guard. Sakanade's blade is straight and slim with the tip ending in a slanted razor-like edge instead of being tapered to a point. There are five holes along the sword's length.
- Shikai Special Ability: Sakanade's Shikai ability creates an "Inverted World". The power is an optical illusion which is caused by the scent the sword gives off upon its release. It inverts an opponents' sense of direction. Shinji describes the release technique as something like a trump card. Up and down, left and right as well as forward and backward are opposite. Though not just the sense of direction is changed. The opponent's eyesight and where they get cut is reversed as well. Shinji claims that countering the damage from the inverted directions simply by processing it all within the mind is not possible. No matter how powerful the opponent even if one is accustomed to fighting in that particular way, their body will not adapt and will continue to fight by reflexes, which causes it to continuously succumb to the powers affect.
Hollow Mask: Shinji's Hollow mask strongly resembles a pharaoh's mask, with a short, flowing hood hanging down the back of his neck. When donning his Hollow mask, Shinji's sclera turn completely black and his irises become dark grey.
- Power Augmentation: While wearing the mask, Shinji's Hollow powers supplement his Shinigami powers, giving him a vast increase in both strength and speed.
- Enhanced Strength: While wearing his Hollow mask, Shinji has shown that he gains greater strength, which he uses to physically overwhelm Tōsen and Grimmjow.
- Enhanced Speed: While wearing his Hollow mask, Shinji is able to move much faster, which he uses to overwhelm Tōsen and Grimmjow on separate occasions in terms of speed.
- Enhanced Endurance: With his Hollow mask, Shinji becomes much more resilient to pain. He even states that when he first underwent Hollowfication that "wearing the mask feels like being in control of someone else's body".
- Cero: Shinji gathers energy that is displayed in a horizontal line at his fist. He then releases a crimson Cero with an extremely wide arc and devastating force. The power of the Cero from a distance is powerful enough to cause grievous injury to an Espada of at the rank of No. six, even at minimal power.
- The Visored
- Kensei Muguruma
- Rōjurō Ōtoribashi
- Love Aikawa
- Hachigen Ushoda
- Lisa Yadomaru
- Mashiro Kuna
- Hiyori Sarugaki (Close friend)
- Ichigo Kurosaki (Hollowfication student)
- Karin Kurosaki (2nd Hollowfication student)
- Momo Hinamori (Lieutenant)
- Orihime Inoue
- Kisuke Urahara
- Yoruichi Shihoin
- Tōshirō Hitsugaya
- Rangiku Matsumoto
- Shunsui Kyōraku
- Jūshirō Ukitake
- Ryuha Armament Alliance
- Sōsuke Aizen (Arch-enemy)
- The Arrancars
- The Espada