Akaza (猗あ窩か座ざ Akaza) is a member of the Twelve Demonic Moons, holding the position of Third Superior Moon.  When he was human, his name was Hakuji (拍はく治じ Hakuji).
As a Demon, Akaza took the form of a muscular young man with skin so fair that it appears white tinged with bright green, adorned with a pattern of thick blue lines, which resemble the criminal tattoos he had as a human. The lines on his face curved across each of his eyes from under his ears to above his temples, another blue line running from the center of his hairline to the bridge of his nose, with two more lines running around his neck, three more branching off from the bottom line toward his torso.
The center line ran directly down his chest to halfway down his belly, and the other two branched off to the sides on either side of his chest to join the other two lines, with this same three-line pattern also repeating around his waist.
On her arms, lines ran down the front of her shoulders and joined two more lines that went around her biceps, before continuing down to her wrists, under which each of her fingers could be seen to be equally dark blue with an orange nail, her toes also sharing this unusual appearance.
Akaza had short bright pink hair that fell around his head, and inwardly slanted yellow eyes with pink lashes and blue sclera that looked like cracked glass, the kanji for "Upper Rank Three" etched into their irises.
He wore little clothing, only a short, sleeveless, dark pink-purple haori cut at the waist, left open to expose his chest, which was decorated with a square pattern on the back. Underneath, he wore a pair of white baggy pants that he rolled up to his knee, with a blue rope belt to hold it at the waist. Akaza prefers to go barefoot, but wears a chain of large round beads around each of his ankles.
When he was human, as Hakuji, he had the same hair, but black rather than pink, and pale blue eyes with unusually colored pink lashes. He was also very muscular as a human, and on each of his forearms he had three black criminal tattoos.
He wore a dark blue-gray yukata.
Akaza is a strong, stubborn and impulsive demon who loves to fight, especially against strong demon killers. He despised anyone he deemed weak, but sincerely respected those who were strong in his eyes, regardless of race. Whenever he met someone he considered strong, he demanded to know their name, and would not stop until he found out; he remembered all the names he memorized as a tribute to their strength. Akaza had a deep-seated psychological need to become stronger, and did not get along with his higher-ranking comrades because he saw them as his rivals. He was particularly antagonistic towards the two Higher Ranks above him, Doma and Kokushibo, and even seemed jealous of them, lashing out at Doma and vowing to kill Kokushibo. 6] Even after being beaten and decapitated in his fight against Tanjiro Kamado and Giyu Tomioka, he was stubborn and continued to fight without even knowing why he wanted more power. As a human, Hakuji possessed the same stubborn personality with a big heart and resilience. He valued others more than his own well-being and hated himself for having a life "full of empty words and promises. Even after becoming a Demon and losing his memories of his human life, parts of Hakuji's memories influenced Akaza's decisions; he refused to eat women, even though he knew it would make him stronger. His hatred of weak and cowardly people comes from a corruption of his human memories, where a rival dojo poisoned the well of his dojo because he was never able to beat it. Later, after remembering his entire past and all of his regrets as a human and demon, Akaza began to openly hate himself and all of his shortcomings during his life where he was not there to save or protect everyone he loved and cared about, and later admitted that the person he really wanted to kill all along was himself.
Demonic abilities: Overdeveloped Speed: Akaza is extremely fast. During his fight with Kyojuro, Tanjiro states that they were moving so fast that his eyes could not follow their movements. 
Overdeveloped strength: Akaza possesses enormous physical strength, as he shows when he easily breaks Giyu's sword in half with a single side punch despite the fact that Giyu was waving his blade downwards. 3] He is able to easily destroy the head of Doma, the Second High Moon, with his arm and easily pierce Kyojuro's stomach. With his Blood Power, he is able to cause a crater in the ground just by hitting it.
Overdeveloped Regeneration: Akaza has incredible regeneration. He is able to regenerate from wounds inflicted by Tanjiro and Rengoku and even from lost limbs inflicted by Giyu with little effort. During his fight against Giyu and Tanjiro, his regeneration has evolved even further. He is able to survive even after having his head cut off  and is then able to regenerate a new one,  a feat that only Muzan had accomplished before.
Akaza has a unique ability called Technique Deployment. 6] After deploying his technique, Akaza uses his ability to create various shockwave-like attacks. He can also track his opponents by tracing their bloodlust.
Destructive Murder (破は壊かい殺さつ Hakai satsu) is a martial art, probably adapted from the Soryu style hand-to-hand combat that Akaza mastered as a human, now enhanced with his demon abilities.
Tactical Intellect: Akaza is a genius among geniuses when it comes to unarmed and hand-to-hand combat, especially those related to martial arts. He also showed natural talent and ability in martial arts, including being able to defeat talented swordsmen and fighters from nearby dojos while learning the Soryū style from Keizo. Even as a child, Akaza could fight based on pure instinct and tactical intuition and win. This ability even surprised Giyu Tomioka, who said that Akaza could instantly evolve and adapt to any attack or technique he used, to the point where he could predict when his opponents would strike and how to counter them with equal power.
Immense regeneration: Akaza has one of the most incredible regeneration abilities in the series. He is able to regenerate from wounds inflicted by Tanjiro and Rengoku and even from lost limbs inflicted by Giyu without much effort. During his fight against Giyu and Tanjiro, his regeneration has evolved further. He is able to survive even after having his head cut off and is then able to regenerate a new one, a feat that only Muzan had accomplished before.
Enhanced Senses: Like all high ranking demons, Akaza has sensory abilities beyond those of humans. He demonstrated this on several occasions when he was able to sense the caliber of his opponents, as he did with Kyojuro Rengoku, simply by looking at them. His senses were so sharp that even Giyu Tomioka recognized him .
Extrasensory Perception: This is a special extension of Akaza's senses, obtained through years of honing his fighting instincts and supernatural abilities acquired while he was a demon. His ESP ability comes in the form of his Deployment of Techniques: Destructive Death - Compass Needle. This ability allows Akaza to gain information about his surroundings and opponents, even if they are far away from him, while giving him an accurate idea of their physical weaknesses.
Blood Demon Art
Shockwave Generation: Akaza's Blood Demon Art gives him the ability to generate shockwaves from the pressure created by the superhuman strength of his fists and legs when he strikes. The shockwaves have the appearance of the same shade of blue as his tattoos and can be triggered from near or far. The power of the shockwaves can range from throwing opponents to creating craters in the ground. This ability, combined with his superhuman strength, makes him a formidable opponent in close or distant combat.
Indomitable Will: Akaza has an unshakable will and spirit. Although he was decapitated by Tanjiro's Nichirin Blade, he refused to disintegrate and die, instead forcing his headless body to continue fighting. He pushed his regeneration to the point where he could regrow his head, simply because he refused to let himself be lost. Even before he became a demon, he was constantly taking hits from opponents much larger than himself and receiving countless blows, all because he wanted to heal his sick father.
Master of Unarmed Combat: Akaza's most remarkable ability, both as a human and as a demon, is his supernatural ability in unarmed combat. Even before transforming into a demon, Akaza demonstrated prodigious skills in various forms of close-range combat, being able to intuitively create his own fighting style that proved capable of annihilating several grown men by the age of 11. 18] By the age of 18, he was able to annihilate 67 adult kendo masters with his fists alone. Furthermore, when combined with his Blood Demon Art, it makes each of his blows and strikes incredibly deadly, making him unmatched in hand-to-hand combat and martial arts skills.
Soryū Style (素流そりゅう式しき Soryū Shiki?): A bare-knuckle martial arts style taught to him by Keizo when he was living with him and taking care of Koyuki. He used it to kill 67 kendo masters with ease and it was the main inspiration for his Destructive Death style used when he became Akaza.
Bell Crusher (鈴すず割わり Suzu Wari?): A technique presumably created or inspired by the Soryū Style where Akaza strikes a sword to the side as it comes down to break it with ease.
Akaza has a unique ability called Technique Development (術じゅつ式しき展てん開かい Jutsushiki Tenkai?). Akaza begins by initiating a unique posture in the Soryū style. Currently, there are 2 versions of this posture. The first is performed by bending his knees into a semi-crouched position, extending his right arm with a half-closed fist facing his body, and bending his left arm with an open palm; the second version is almost identical, except that he opens his palm on his right arm while fully clenching his fists in a downward bend on his left arm.