Akaza/Synopsis

Human Life
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 local dojo. Annoyed by the man's cheerful demeanor, Hakuji challenged him to a fight, but was defeated with ease.

Keizo then 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 caring for his father, he had little trouble, though he found it awkward when she burst into tears seemingly at random. One of those times, unbeknownst to him, he had indirectly motivated her by telling her that "there will be a next year" to see a local fireworks show.

One day, he discovered that Koyuki had been forced outside and left there by the heir of the nearby kenjutsu dojo that sought Keizo's land for themselves and prevented him from getting any students before Hakuji. Enraged, Keizo and Hakuji fought the dojo, and after defeating nine people, Hakuji made them promise to never get involved with the Soryuu dojo or Koyuki again. The heir of the rival dojo became enraged and swung a sword at Hakuji, only for him to use his Bell Splitter technique and punch the side of the blade, breaking it. The other members of the dojo were so moved by the beauty of this technique that they accepted their loss and apologized for the rudeness of the heir, leaving the Soryuu dojo in peace.

Two years later, Koyuki's health improved enough that she could stand and do chores. Hakuji continued training as Keizo's pupil of the Soryu style, and the dojo began to grow. One day, Keizo offered to let Hakuji 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.

The heir of the rival dojo heard about Hakuji's marriage to Koyuki, so he gathered some angered disciples and fought Hakuji, but they lost. Tragically, this victory was short-lived. Hakuji went to visit his father's grave to inform him of his marriage, but quickly realized something was amiss upon his return. A student from the dojo informed him that the rival dojo had poisoned the well 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 Kibutsuji'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 Kizuki. Hakuji, with nothing left to protect and having lost his will to live, accepts and becomes the demon Akaza.

Demon Life
After transforming, 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 or harm women. Due to his strength, loyalty and will to become stronger, he became one of Muzan's favourites and dispatched him only for special missions, such as searching for the Blue Spider Lily.

During his time as a Demon, Akaza noted that he had met and battled several Hashira of the Demon Slayer Corps during his hundreds of years of life. During these meeting, Akaza had invited every single one of them to become a Demon due to Akaza liking the natural strength, genius and skill the Hashira had possessed, wishing to continue battling against them forever. However Akaza was turned down by every single one of them due to them wanting to stay as humans, causing him much confusion as he could not understand their desire to stay as humans.

Although not exactly specified, it has been stated by Akaza that each of the Hashira that he battled did not use the Flame Breathing, showing that his battle with Kyojuro Rengoku was the first time he had come across a Flame Hashira.

Fifty years prior to his battle and death against Tanjiro and Giyu in the Infinity Castle, Akaza had come across and battled a powerful Water Hashira of noteworthy skill and power in the usage of the Breathing Style and successfully killed him and for the next half century did not come across anyone else of the same skill level until his duel against Giyu.

Mugen Train Arc
Akaza appears shortly after Tanjiro, Kyojuro, Inosuke, Zenitsu and Nezuko have defeated Enmu and rescued the passengers. Noticing a downed Tanjiro, he immediately rushes forward to kill him, when Kyojuro stops the attack and slices his arm in half. Quickly healing the wound and complimenting his blade, Akaza is then asked why he would attack an already injured person, to which he states he simply wanted to rid him quickly before talking to Kyojuro. Deeming him as at the peak of his fighting spirit as a Hashira, he attempts to persuade him to become a demon. He states that as a human, he would eventually become old and die, whereas as a demon, he could continue to become more powerful. When Kyojuro repeatedly refuses the offer and refutes his statements, an annoyed Akaza declares he would instead kill him, and activates Destructive Death: Compass Needle.

Akaza and Kyojuro battle fiercely, with Tanjiro and Inosuke looking from a distance, both knowing the two are on a completely different level of power. Akaza is repeatedly cut but instantly regenerates his wounds, all while taunting Kyojuro by saying all the Hashiras he had killed had never once taken his offer to change. The demon launches in the air and hits Kyojuro with Air Type, knocking him back temporarily, though the attack is quickly beaten. Knowing a battle at a distance will be difficult, the Flame Hashira rushes forward and tries to attack up close, though all his swings are deflected and dodged. Akaza again taunts him for his weakening human stamina compared to his demonic physiology and tries again to persuade Kyojuro to change, which fails as Kyojuro repeats he will not become like him. They trade attacks again, with even Inosuke noting that if he tried to help Kyojuro, he would be too slow and killed instantly. Akaza starts to make contact with his attacks, severely injuring the Hashira. All of Kyojuro's sword blows are futile with the demon's rapid healing abilities and he starts to become desperate with multiple Flame Breathing attacks. Akaza suddenly backs away, allowing Kyojuro to catch his breath, only for Tanjiro and Inosuke to see him bleeding profusely, in contrast to a completely fine and healed Akaza.

Akaza, once again, taunts Kyojuro for his numerous injuries, whereas his had already healed instantly because of being a demon and for fighting a losing battle as a human. Kyojuro's body suddenly becomes engulfed in fire, declaring he will fulfil his duty as a Hashira, to the demon's confusion and wonder. Kyojuro decide he would try to injure him as much as possible, even if it means dying, and speeds forward with Flame Breathing: Esoteric Art. Akaza is amazed at his opponent's fighting spirit, and decide he must become a demon so they can battle forever. Declaring he is the Flame Hashira, he uses Flame Breathing, Ninth Form: Rengoku, and rushes forward. Akaza responds with Destructive Death: Annihilation Type. They hit each other; with Kyojuro slicing Akaza's arm, torso and almost through his neck, and Akaza driving his arm through Rengoku's solar plexus. Akaza desperately begs him to become a demon, knowing the wound he inflicted is fatal and amazed at his opponent's will to fight, declares him one of the few chosen strong ones. Kyojuro refuses once more, remembering his mother's promise to him to protect the weak, and drives his sword deeper through his neck, even catching his fist when Akaza tries to punch him with his free hand, shocking the demon. The sun begins to rise and Akaza attempts to flee but is held in place by Kyojuro refusing to surrender. Tanjiro and Inosuke attempt to aid the Hashira, Inosuke using Fang One: Pierce to attack the demon. Akaza suddenly rips off his own arms from Kyojuro's body and stomps the ground, creating a shockwave to knocks Inosuke away and giving him the chance to flee. Tanjiro frantically gives chase and hurls his Nichirin Blade at the Upper Moon, piercing his chest. Akaza hears Tanjiro's cries, calling him a coward for retreating, enraging him as he mutters to himself that he was fleeing from the sun, not him. Deciding the battle over and Kyojuro will soon die, Akaza flees to safety in the forest, leaving Inosuke and Tanjiro with a dying Kyojuro.

Entertainment District Arc
Akaza appears before Muzan and reports to him that he could not find the Blue Spider Lily, instead, he took down one of the Hashira. Muzan retorts it was only one Hashira and declaring his desire is for all to be dead. Angered at his failure, Muzan takes control of Akaza's cells and causes him to bleed heavily. The Demon Lord mocks him for acting proud when three other demon slayers were still alive and he could have killed them as well, ending his rant by claiming "even Upper Moon Three was brought to the ground". When dismissed by Muzan for his failure, he takes notice of Tanjiro's nearby blade. Remembering how he called him a coward, he furiously smashes it to pieces and declares he would spill his brains the next time they meet.

Some time later, Akaza is suddenly transported to the Infinity Castle by Nakime. He is greeted by Gyokko and Hantengu but is disinterested in talking to them. He asks the Biwa Demon on Muzan's whereabouts and where is Upper Moon One when he is cheerfully greeted by Doma. Annoyed by his attempts to have a conversation with, he irritably asks Doma to take his arm off him, then violently shatters his jaw when he doesn't. An unfazed Doma continues trying to talk and evens believes the attack is simply a sign of their "friendship". Nakime answers his question and states that Upper Moon One is the first to arrive, who then announces Muzan's appearance. Muzan voices his disappointment in Gyutaro and wonders aloud why the Upper Moons are still around with no longer a proper purpose, shocking them all; Akaza himself doesn't respond knowing his recent failure. Gyokko suddenly states that he has new information for their leader and Doma unwittingly asks if he can participate in a mission, causing Akaza to angrily destroy his superior's head for "disobeying Muzan's orders".

Suddenly, his hand falls off, and Kokushibo appears before him, reprimanding him for disrupting the hierarchy. A regenerated Doma tries to calm down Upper Moon One but he angrily tells Akaza if he wanted to take Doma's place and beat him, he should do so in a proper battle. A silent Akaza overhears Doma's statement that such a battle would be fruitless, since even the more recently turned Doma is far more powerful than he is, earning his ire. Doma continues to try defending Akaza but Kokushibo directly asks him if he understood what he declared. Akaza complies but quietly threatens to kill him as well. As Kokushibo disappears, Akaza rushes out of the Infinity Castle, ignoring Doma's attempts at another conversation.

Infinity Castle Arc
During the Infinity Castle Arc, Akaza appears causing a powerful tremor throughout the area in which Tanjiro and Giyu are near. He then appears from above breaking through the roof over Tanjiro and slamming into the ground. “It sure has been a while. I’m surprised your still alive being the weakling you are.” Akaza immediately charges toward Tanjiro unleashing an attack toward him. The attack is however avoided which leads into a short clash between Akaza and Tanjiro which ends in Tanjiro successfully landing a few slashes on Akaza without major injury. Akaza surprised by Tanjiro’s growth admits that Kyojuro was right and that he wasn’t weak. Showing his respects toward Tanjiro, Akaza uses his Technique Development commencing the battle. Giyu and Akaza engage combat, Akaza stating that it had been 50 years that he ran into someone as good as Giyu, the current Water Hashira. Noting toward Giyu’s special Dead Calm technique, a form Akaza had not seen before from any other Water Hashira. Tanjiro joins the battle and attacking along with Giyu both face Akaza. The demon keeping up with the both of them evading while striking back, managing to overpower their techniques at times. Akaza enjoying the battle compliments Giyu’s techniques and asks for his name wanting to remember the Water Hashira. Giyu refuses and tells Akaza to not talk to him, in which Akaza replies saying he loves to talk asking for his name again. Before releasing a flurry of powerful kicks in which results in Giyu being launched through multiple walls of the Infinity Castle. Tanjiro yells out Giyu’s name, which Akaza notes. Akaza and Tanjiro clash for a little while before Tanjiro is momentarily overpowered and pushed back.

Akaza commends Tanjiro’s movement, praising him for his growth and training. Claiming that his growth makes Akaza glee with happiness. Akaza goes onto say that he was glad Kyojuro died that night, and that he wouldn’t have grown stronger. Akaza finding his worldview and want to stay human dumb. Tanjiro angered by Akaza’s words tells him to stop talking, and that he’s just badmouthing Kyojuro despite Akaza seeing it as praising him. Akaza explains that he only hates weaklings, and that the law of nature depicts that they should be eliminated. Tanjiro explains otherwise and that the strong should protect the weak, and that they way Akaza things is unforgivable. Akaza hearing Tanjiro’s words feels irritated and and unpleasant. Akaza becomes puzzled as to why he still is unhappy with Tanjiro’s strength. Originally believing it was because he was weak, however he doesn’t feel any pleasure or happiness despite the slayer becoming stronger he realizes. He deduces it down to it being Tanjiro’s mere presence and everything about him being unpleasant and irritating. Akaza suddenly hears and feels the touch of his former teacher, his teacher saying similar words to Tanjiro. Akaza instinctively releases a backhand toward the figure he thinks is there. He faces Tanjiro once more stating how truly unpleasant he is before releasing powerful oppressing techniques toward the slayer. Akaza’s techniques piercing through Tanjiro’s defense with ease and precision. Tanjiro managing to release a strike at which slightly cuts Akaza’s neck. Akaza intrigued by the attack due to the fact, he thought he dodged it however damage was still of result. The two clash on before Akaza gains a grasp of Tanjiro’s sword between his hands. Tanjiro uses all the physical means and options he can to try and get Akaza to let go, most proving fruitless before Akaza’s hands are slashed off. Giyu reappears on the battlefield, the battle pausing for a brief moment. Giyu charges toward Akaza dodging Akaza’s attack and attempting to strike toward his neck. Akaza dodges the attack noticing that the Hashira had unlocked their Demon Slayer Mark, their speed becoming faster as well. Giyu lands a few strikes on Giyu, out speeding the demon for a short while before Akaza immediately after caught up and matched his speed. Akaza and Giyu continue to clash as Tanjiro jumps in for a moment but is immediately noticed and stopped by Akaza. Tanjiro only barely managing to avoid Akaza’s attack and get out the way as Giyu and Akaza continue to fight on. Akaza manages to land a fatal attack on Giyu after a while, the demon starting to anticipate the Hashira’s attack forms. Akaza goes on to end the battle in that moment, as Giyu has run out of forms to use. Giyu’s Nichirin Blade is broken soon after when he attempts to slash Akaza’s arm. Giyu unable to defend himself, Akaza attempts to impale him with his fist. However before the attack can land, his hand is slashed off by Tanjiro. Akaza’s senses tell him to kill Tanjiro immediately, Akaza able to tell that something about Tanjiro has changed. Akaza using his Technique Development goes on to release his most powerful technique  Final Form: Blue Silver Chaotic Afterglow. Akaza’s technique lands a number of blows on Giyu, but the Hashira survives the technique. Akaza unsurprised that the Hashira was able to survive the technique goes on to say “Don’t die like Kyojuro and like Tanjiro”. Seemingly unable to perceive Tanjiro’s presence as he is still alive and only just behind Akaza. However Tanjiro suddenly yells out at Akaza while dashing towards him, Akaza caught off guard strikes toward him. Tanjiro avoiding the attack. Surprised that Tanjiro is even alive and that he was unable to sense him, he uses his Compass Needle technique to detect Tanjiro’s attacks. However to his surprise he is unable to sense anything from the slayer, Tanjiro’s Battle Spirit completely erased. Able to perceive an attack is coming, Akaza tries to calm himself down but however despite his attempts. Tanjiro avoids Akaza’s attack using Transparent World and Selfless State and counters by decapitating the Uppermoon.

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Akaza/Sinopsis