In short
Akaza does not kill women because of Koyuki, the young woman he was to marry when he was still a human named Hakuji. She died of poisoning along with her father, and even after becoming a demon and forgetting everything, Akaza keeps refusing to kill or eat a woman. He knows this rule slows his progress and keeps it anyway, unlike Doma, who prefers to devour women.
Contents
Akaza kills Rengoku at dawn, breaks swords with a punch and despises everyone he considers weak. He is one of the most feared demons in Demon Slayer, and yet there is one thing he never does: he does not kill women, and he does not eat them.
This detail puzzled fans for a long time, because the series sets it up without explaining it. The answer comes late, in the Infinity Castle, and it changes how you see the whole character. Our page on the demons of Demon Slayer and their Moons places Akaza among Muzan’s other demons.
The short answer: the memory of Koyuki
| Question | Answer |
|---|---|
| What he refuses | to kill a woman, or to eat one |
| Where the rule comes from | from Koyuki, his fiancée when he was human |
| Does he remember it | no, he forgot everything when he became a demon |
| What it costs her | slower progress, and he knows it |
| His opposite | Doma, who prefers to devour women |
| When it all becomes clear | in the Infinity Castle, facing Tanjiro and Giyu |
Before he was Akaza, his name was Hakuji. He loved a sick young woman, Koyuki, nursed her for years and promised to protect her all his life. She died before their wedding, poisoned.
Once a demon, Akaza lost the memory of that life. He no longer knows who Koyuki was or why he refuses to touch women. The rule outlived the memory, like a reflex whose origin he has forgotten.
That is what makes the character so special in Demon Slayer. A demon who has killed hundreds of people stays faithful, without knowing it, to a promise made to just one.
A promise without a memory
Akaza has forgotten Koyuki, but not the promise he made her. He keeps it for more than two centuries without knowing why.
A rule he follows without remembering it
When Muzan turns a human, he erases most of their memory. Akaza keeps only fragments of his past life: the desire to be strong, contempt for the weak, and this refusal he cannot explain.
He almost never comments on it. To him, that is simply how it is: women are not opponents, and he does not feed on them. The Demon Slayer series, for that matter, never puts him up against a female demon slayer, as if the story itself respected this limit.
The other demons know it. Doma openly mocks him for it, and Muzan tolerates it, because Akaza makes up for it with a fighting power few demons can match.
The reader, at first, has only a clue and a riddle: a demon who thinks of nothing but getting stronger gives up what could help him do so. The answer lies in the past he has forgotten.
A limit he cannot explain
Akaza does not know why he refuses to kill women. He only knows that he will not do it.
What this rule costs him
In Demon Slayer, a demon grows by eating humans. The more he devours, the more powerful he becomes, and some meals count more than others.
Doma says it bluntly: women are supposedly more nourishing, and that is why he chooses them. By forbidding himself to eat them, Akaza deliberately deprives himself of part of what could make him stronger.
He knows it, and he keeps his rule. He climbed to the rank of Upper Moon Three another way, through training and combat, facing ever stronger demon slayers instead of devouring crowds.
This way of progressing suits him. Akaza loves fighting for its own sake, counts his opponents’ years of training and respects those who stand up to him. He remembers the faces of the demon slayers he defeated, rarely those of the people he ate. Our article on Akaza, Upper Moon Three details his techniques and his fights.
Stronger without cheating
Akaza becomes Upper Moon Three by refusing the meals that would have made him stronger. He prefers to win through combat.
Frozen in his guard, fists clenched and blue marks on his arms, Akaza stands on an engraved base that lights up, in the collection dedicated to Akaza.
Light-up Akaza figure
Resin figure, Akaza on guard, fists clenched, on an engraved, illuminated acrylic base.
View the product · €64.90Hakuji, before Akaza
The story begins in Edo, in the poor districts. Hakuji is a poor boy with a violent temper, who steals to pay for his sick father’s medicine.
He is arrested several times and tattooed on the forearms each time, the mark imposed on thieves. His father ends up hanging himself, so that his son will stop stealing because of him and live honestly.
Hakuji wanders, fights, hits everyone who crosses his path. It is a man named Keizo, master of an unarmed combat dojo, who brings him down effortlessly and offers him a roof. In return, he asks him to look after his sick daughter.
Our article on Akaza’s story, from Hakuji to the demon tells this life in detail, and our page on all the Demon Slayer characters presents Keizo and Koyuki among the others.
The blue lines on his arms
The blue lines covering Akaza’s body echo Hakuji’s thief tattoos.
Koyuki, the promise under the fireworks
Koyuki is frail, often bedridden with fever. Hakuji nurses her for years with a patience nobody knew he had, carries her on his back, watches over her at night.
One evening, she regrets not being able to go and see the village fireworks. Hakuji replies that he will take her the following year, and every year after that. She slowly recovers, and the fireworks become their own special moment.
Keizo asks Hakuji to take over the dojo and marry his daughter. Koyuki asks him whether she can become his wife, and Hakuji promises to become stronger to protect her all her life.
That is the promise the demon will keep without knowing it. Protecting Koyuki meant never letting a woman suffer at his hand, and Akaza never raises a hand against a woman in the whole of Demon Slayer.
The couple under the petals, Akaza on one side and Koyuki on the other, forms a 26.5 cm diorama among the figures from the whole series.
Akaza and Koyuki diorama 26 cm
26.5 cm diorama, Akaza and Koyuki on a shared base, petals added at the bottom.
View the product · €99.90The poisoned well
The happiness does not last. Hakuji goes to pay his respects at his father’s grave to tell him about his wedding, and while he is away, the neighbouring dojo poisons Keizo’s well.
These neighbours practised swordsmanship and had never managed to beat Hakuji. Unable to win fairly, they strike at the weakest. Keizo and Koyuki both die.
Hakuji, mad with grief, goes to the rival dojo and kills with his bare hands the sixty-seven men inside. The massacre is such that Muzan at first thinks it is the work of a demon.
He comes to see the culprit, finds him, and turns him. Hakuji disappears, Akaza is born, and the memory of Koyuki fades with everything else.
Sixty-seven men
Hakuji alone, with his bare hands, kills the whole dojo that poisoned Koyuki. Muzan finds him there and turns him.
Doma, his exact opposite
To measure Akaza’s rule, you only have to look at Doma. Upper Moon Two prefers to devour women, in the name of their nutritional value, and boasts about it with a smile.
Doma is the demon who ate Kotoha, Inosuke’s mother, and who kills Shinobu in the Infinity Castle. Everything Akaza forbids himself, he does with pleasure.
Akaza cannot stand him. At the Upper Moons meeting, when Doma puts his arm around his shoulders, he blows his head off with a punch. Doma regenerates laughing, which annoys him even more.
This hatred takes on another meaning once Akaza’s past is known. Without knowing it, he hates in Doma everything Hakuji had sworn never to do. Our article on Doma, Upper Moon Two tells the story of this demon who feels nothing.
Their ends extend the contrast. One dies finding the woman he loved, the other dies without ever having felt anything for anyone, and Demon Slayer holds on to this contrast to the very end. Akaza, Doma and the other Moons are found in the Demons collection.
Two demons, two ends
Akaza dies finding Koyuki again. Doma dies without ever having loved anyone.
Koyuki everywhere in his techniques
Akaza’s memory is erased, but Koyuki is everywhere in the way he fights. The clues are laid from his first appearance in Demon Slayer, long before anyone can understand them.
His best-known technique makes a snowflake-shaped disc appear under his feet, which lets him sense his opponents’ will to fight. Koyuki’s name contains the character for snow, and she wore three snowflake-shaped hairpins.
Almost all his attacks bear the names of fireworks, echoing the promise to take her to see them. His unarmed fighting style is the one Keizo taught him at the dojo.
Even his colours come from her. The pink of his hair and his vest echoes that of Koyuki’s kimono, a detail specified in the manga’s bonus pages.
Rereading Akaza’s fights with these keys changes everything. Against Rengoku as against Giyu, each attack he announces silently recalls an evening of fireworks with Koyuki, and it is one of the most successful devices in Demon Slayer.
A snowflake under his feet
The snowflake-shaped disc Akaza unfolds in every fight echoes Koyuki’s hairpins.
The short red vest, the bodysuit printed with blue lines and the white trousers make up the Infinity Castle Akaza cosplay, among the cosplay outfits from the whole series.
Akaza cosplay
Short red vest, bodysuit with blue lines, gloves and baggy white trousers, from S to XXL.
View the product · €119.90Why does he hate the weak?
Akaza’s contempt for weakness comes from the same tragedy, distorted by forgetting. Those who killed Koyuki were cowards, too weak to beat Hakuji face to face, who went after a sick young woman.
Once a demon, Akaza keeps his hatred of the weak without remembering where it comes from. He insults Tanjiro, calls him trash, and reserves his respect for the fighters who make him bleed.
That is why he offers Rengoku the chance to become a demon, at the dawn after the Mugen Train. He sees in him a strong man he would like to keep forever, and does not understand that anyone would rather die. Our article on the Mugen Train arc tells this duel up to sunrise.
Deep down, the person Akaza despises most is himself. He was not there when his father died, he was not there when Koyuki drank the water from the well. His whole quest for strength is an answer to these two absences.
The hatred of an absent man
Akaza hates the weak because Hakuji failed to protect those he loved. He has forgotten that, but not the anger.
The day he remembers
In the Infinity Castle, Akaza faces Giyu Tomioka and Tanjiro. Tanjiro ends up cutting off his head, and the demon refuses to die: his body keeps fighting, trying to overcome the weakness of his neck.
That is when the memories come back. He sees his father again, Keizo, and above all Koyuki, who begs him to stop. He understands what he has done with the promise and with his master’s school, by putting them at the service of murder.
Akaza then chooses to die. He turns his own technique against himself and destroys himself, when he could have risen again. Koyuki welcomes him in tears, and the two leave together.
For many viewers, this is the moment Akaza stops being just another Demon Slayer villain. The demon who refused to kill women had been, from the start, a man mourning his own, and his last decision is to finally keep the promise made under the fireworks.
This ending is at the heart of the first Infinity Castle film, released in France in 2025. Our article on the first Infinity Castle film looks back at this fight, and our page on all the Demon Slayer arcs places it in the timeline.
