Akaza

Akaza was a member of the Twelve Demon Moons, holding the position of Upper Moon Three. While he was human, his name was Hakuji.

Appearance
As a demon, Akaza has pink hair and eyelashes, yellow eyes with blue sclerae, blue markings all over his body, and white skin.

During his human days as Hakuji, he had black hair, blueish eyelashes, and blueish eyes. Each forearm had three black criminal tattoo lines.

Personality
Akaza is a strong, stubborn and impulsive demon who enjoys fighting, especially strong Demon Slayers. He looks down on anybody he deems weak, but genuinely respects those who are strong in his eyes, regardless of race. Once he meets someone he deems strong, he demands to know their name, and will not stop until he finds out; he remembers all the names he's committed to memory as tribute to their strength.

Akaza has a deeply-rooted psychological need to become stronger, and does not get along with his fellow Upper Moons due to seeing them as rivals. He is especially antagonistic towards the two Upper Moons above him, Doma and Kokushibo, lashing out against Doma and vowing to kill Kokushibo. Even after being beaten down and beheaded during his fight against Tanjiro and Giyu Tomioka, he stubbornly held on and continued to fight despite not 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 hates 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 influence Akaza's decisions; he refuses to eat women, despite knowing it would make him stronger if he did so. His hatred of weak, cowardly people stems from a corruption of his human memories, where a rivaling dojo poisoned his dojo's well because they were never able to beat his.

History
Hakuji was born and raised in the slums to a sickly father he deeply loved. In order to pay for medicine, Hakuji pickpocketed from people in town, but was caught three times. The magistrate beat him and marked him with tattoos, threatening to cut his arms off the next time he was caught and calling him a "demon child". When Hakuji returned home after his third beating, a villager informed him that his father, having heard of his arrest, hung himself. In the letter he left, he stated he wanted Hakuji to live a full life and didn't want to take medicine if it was earned by dishonest means.

With his criminal tattoos and no home to return to, Hakuji was eventually banished from Edo. Devastated by the loss of his father and enraged at this society they lived in where he couldn't afford his father's medicine, he picked fights with people and beat them up. One day, after nearly killing seven adult men in a village, he was approached by Keizo, the owner of a dojo in the village. Annoyed by the man's cheerful demeanor, Hakuji challenged him to a fight, but was defeated with ease.

Keizo took him in so he could nurse Koyuki, Keizo's sickly daughter. Her mother, her previous caretaker, drowned herself due to stress and Keizo had to work handyman jobs to keep them afloat, so Hakuji was tasked with tending to her. Already accustomed to tending to his father, he had little trouble tending to her, though he found it awkward whenever she burst into tears. One of those times, unbeknownst to him, he had indirectly motivated her by telling her that "there will be a next year" to see the fireworks.

Three years later, she was in good health and could stand and do chores. He continued training as Keizo's pupil of the Soryu style, and the dojo began to grow. One day, Keizo offered Hakuji to take over the dojo&mdash;and take Koyuki as his bride, to Hakuji's surprise and embarrassment. He agreed, silently vowing to protect both of them, even at the cost of his own life. At a festival, Koyuki told him of her past, asking if he was really okay with the proposal, to which he reaffirmed his vows to her, promising to protect her for the rest of his life.

Tragically, this vow was short-lived. He took a short trip to visit his father's grave and inform him of his marriage, but quickly realized something was amiss upon his return. A student from the dojo informed him that their rivaling kenjustu dojo, which had always sought Keizo's land for themselves and prevented him from getting any students until Hakuji's arrival, had poisoned the well from where Koyuki and Keizo drank water from. The two died shortly after drinking that water while Hakuji had been away.

Enraged, Hakuji killed all sixty-seven members of the rivaling dojo with his bare hands, pulverizing them to the point where their corpses were no longer recognizable. This incident caught Muzan's attention and, though he was disappointed to find it had been a human rather than a demon who'd done such a gruesome act, he decided to make Hakuji one of the Twelve Demon Moons. Hakuji, with nothing left to protect and having lost his will to live, accepts and becomes the demon Akaza.

After becoming a demon, he lost his memories of the time he became a human, with only one single desire to become stronger despite not knowing the reason why he wanted to become strong. Despite this, as noted by Doma, he refused to ever eat women. Due to his strength, Muzan only dispatched him for special missions, such as searching for the Blue Spider Lily.

Red Light District Arc
Akaza appears before Muzan Kubitsuji and reports to him that he could not find the Blue Spider Lily and that he took down one of the Pillars.

Human Abilities
Peak Human Endurance - Prior to being transformed into a demon, Akaza (Hakuji) demonstrated superhuman endurance at the age of 11 as he endured beatings that could make a grown man go numb (100 beatings) thus earning the title of "Demon Child".

Superhuman Strength - At the age of 11, he was able to lay waste to grown men in a fight and at the age of 18, he was easily able to decapitate, dismember and mutilate people with his fists that even Muzan thought that it was a demon who performed these feats.

Soryu Style - A barefisted martial arts style taught to him by Keizo when he lived with him and took care of Koyuki. He used it to kill the kenjutsu students with ease and probably was the inspiration of his Destructive Kill Style used when he became Akaza.

Demon Abilities
Due to being a demon and being the Upper Moon Three of the Twelve Demon Moons. Akaza possess incredible amounts of strength surpassing most demons in the series. He is shown to be able to fight equal grounds against Rengoku, The Flame pillar and eventually land fatal blow on him. Later he is able to fight and overhelm both Tanjirou and Giyu even when Giyu gain his Demon Slayer Mark and Tanjirou increased the power of Dance of the Fire God, he still manage to overwhelm them and would most likely have killed both of them, if he had not lost the will to continue fighting.

Regeneration- Akaza possess incredible regeneration able to regenerate from slash wounds inflict by Tanjirou and Rengoku with little effort and lost limbs inflict by Giyu with little efforts as well. And later during his battle against Giyu and Tanjiro, his regeneration evolved even further and he had became a demon that could no longer be killed via Decapitation, a feat only Muzan has accomplished.

Blood Demon Technique : Akaza has a unique ability called Technique Deployment. After deploying his technique, he can use his ability to create various shock wave-like attacks. He could also track his opponents by tracing their bloodlust.

Destructive Kill:A Type of Martial arts, Likely adapted from the Soryu Style hand to hand combat that he had mastered as a human now further enhanced with his abilities as a Demon.
 * Compass Needle - Deploying a compass underneath him with numbers from 1 to 10. It can detect all incoming attacks through sensing battle spirit.
 * Void Style - Punching the air, he creates a powerful multishot shockwave range attack.
 * War Style - Punching in front of him, he creates large shock waves that fly forward.
 * Obliteration Style - An explosive forward jump followed by a punch that was able to go through Kyoujurou Rengoku's Purgatory attack.
 * Leg Style - Techniques where he uses his legs to attack
 * Cap Tip Slice  - A reverse, rising axe kick he can use to attack behind himself.
 * Flowing Light Flash - Multiple, rapid straight kicks that each produce powerful shockwaves.
 * Ring of a Thousand Flying Planets - Rapid, flowing rising kicks that hit an opponent from below.
 * Dual Layered Demon Wick - He punches rapidly with both arms at once, each producing powerful shockwaves.
 * Crush Style - Techniques that involve crushing attacks from above.
 * Willow of a Thousand Flashes - A powerful downward punch that delivers a large shockwave into the ground, causing massive damage to the ground.
 * End Style - Powerful techniques. Presumably Akaza's strongest techniques.
 * Chaotic Blue Metal Afterglow - Incredibly strong and fast blows that attack from every direction at once almost randomly. They created seemingly thin, sharp shockwaves.

Trivia

 * Akaza was the only demon of the Twelve Demon Moons who refused to eat or kill women, and was given special permission to do so.

Quotes

 * (To Giyu) "Elegant!! This is finely crafted swordsmanship! Splendid! Give me your name! What is it!? I want to remember you!" Chapter 148, page 10.
 * (When Muzan offers to turn him into a demon) "... I don— I... just don't care any... more..." Chapter 155, page 18.
 * (About himself) "But for over a hundred years, I kept pointlessly murdering over and over again. Yet, at the end of the day, it's just a pathetic, comical, uninteresting story." Chapter 155, page 19.

Navigation
Аказа