Infinity Castle: every Upper Moon fails in its own way

The Infinity Castle is not a setting: it is a method. In Demon Slayer: Kimetsu no Yaiba — Infinity Castle, the first part of the final trilogy, released in 2025 (in Japan on 18 July, in Spain and most of the world in September) and whose second part still has no date, the story finally locks the demon slayers and Muzan Kibutsuji's inner circle inside the same impossible building: a labyrinth of tatami rooms that rotates, folds and delivers each combatant exactly where it suits. Whoever moves the rooms decides who meets whom. And in criminology, that has a very specific name.

This article walks through the castle's villains one by one, with the case file kriminis keeps open on each of them. The thesis is simple and slightly uncomfortable: Muzan is the apex, and his profile —the DSM-5's antisocial personality disorder— works as a mold reproduced downward. But no Upper Moon is a copy of Muzan. Each one fails for a different reason, and that variety is precisely what makes the inner circle a case study rather than a parade of monsters.

// The theoryAntisocial personality disorder, in brief

The DSM-5 (American Psychiatric Association, 2013) defines antisocial personality disorder as a pervasive pattern of disregard for and violation of the rights of others, beginning by age fifteen. There are seven criteria, and they are worth reading slowly: repeated failure to conform to lawful norms, deceitfulness —lying, using aliases, conning for profit or pleasure—, impulsivity, irritability and aggressiveness, reckless disregard for the safety of self and others, persistent irresponsibility, and the one that weighs most here, lack of remorse: indifference toward or rationalization of having hurt, mistreated or stolen from another. Diagnosis requires being at least eighteen and evidence of conduct disorder before fifteen.

One nuance gets lost in popular conversation: antisocial personality disorder is not a synonym for psychopathy. The DSM-5 describes a pattern of observable conduct; Hare's psychopathy (PCL-R) adds an affective and interpersonal core —superficial charm, grandiosity, absence of empathy— that not all antisocial individuals display. Most people with this diagnosis are not killers, and many violent offenders do not meet the criteria. We develop it in our file on antisocial personality disorder. In fiction the line is drawn thicker, and Muzan is that line drawn to the very limit.

And then there is the building. The Infinity Castle is, literally, a criminogenic architecture: a space designed so that predator and prey converge while the prey can neither flee nor be helped. Cohen and Felson (1979) explained through their routine activity approach that a crime occurs when three things converge in time and space: a motivated offender, a suitable target and the absence of a capable guardian. The castle deliberately manipulates the third factor: it separates the Hashira, isolates each slayer, prevents anyone from covering anyone else. This is not gothic set dressing; it is engineering of opportunity.

Read Muzan Kibutsuji’s full case file · Antisocial personality disorder →

// The apexMuzan Kibutsuji: the antisocial mold

Muzan meets the DSM-5 list almost point by point, and his biography explains it without excusing it. He was a dying human turned by an experimental treatment into something that does not die of old age, and his first free act was to kill the doctor who gave it to him. Since then he has lived under a thousand identities —merchant, family man, child—, changing face and name whenever it suits him. That instrumental deceitfulness is not an ornament: it is the manual's criterion, sustained lying for profit, practiced for a thousand years without a single crack of guilt. His case file sums it up bluntly.

What defines his profile is not violence but the lack of remorse. Muzan kills his own subordinates for crossing him, for failing, for thinking too much, or simply for existing at the wrong moment, and he registers none of those acts as harm. The irritability of DSM-5 criterion 4 appears in its purest form: aggression is not a means to an end, it is an automatic response to frustration. In his head there are no victims, there are parts. A demon who disappoints is not someone he betrayed: he is defective material.

And yet the trait that portrays him best is the most human of all: fear. Muzan has spent a thousand years fleeing sunlight and a single sword, and his whole empire —the Moons, the castle, the obsessive hunt for the blue spider lily— is the infrastructure of that terror. There lies the character's criminological paradox: the top of the pyramid is not a sovereign being but the most cowardly of them all. His tyranny is panic management. Understanding that does not discount a single one of his deaths; it only explains why he needed so many.

// Upper Moon OneKokushibo: fraternal envy and relative deprivation

Kokushibo —Michikatsu Tsugikuni before he sold his humanity— is Upper Moon One and the most uncomfortable villain of the set, because his fault is the most recognizable. He was not born poor or despised: he was born beside a twin brother, Yoriichi, who did effortlessly what he pursued with samurai discipline. Kokushibo does not measure himself against the world, he measures himself against one single person, and before that mirror any achievement of his own becomes insufficient. kriminis files him under relative deprivation, the theory of Stouffer and Runciman: what hurts is not what you lack in the abstract, but the distance relative to a benchmark you compare yourself to.

What is revealing is that becoming a demon did not close the gap. Kokushibo accepted Muzan's blood so as not to die and to «become a magnificent being», and four hundred years later he is still measuring himself against his brother's memory. His technique is a corrupted version of Yoriichi's Sun Breathing; his six eyes, the literal exaggeration of wanting to see more. Relative deprivation works this way even after winning: as long as the benchmark exists —alive or in memory—, no amount of power suffices. His case file records him as envious, disciplined and relentless, in that order.

And here is the anchor that stops the theory from becoming an alibi: Yoriichi came from the same house, the same father and the same childhood of contempt —worse, in fact, since he was the sidelined twin— and he chose to protect. Two men facing the same home, two opposite answers. The pressure was identical; the decision to drink that blood was not. Kokushibo killed Muichiro, the Mist Hashira, and Genya not because his brother was brilliant, but because he decided that being magnificent was worth more than being human.

// Upper Moon TwoDoma: the emotional emptiness that smiles

Doma is the cleanest case in the inner circle and the most disturbing, because there is no grievance to tell. Raised as a cult leader from childhood, worshipped as the avatar of a god he never believed in, Doma discovered early that he felt nothing: not for his followers, not for his parents dying in front of him, not for the women he devoured after listening to their confessions. kriminis files him under psychopathy, and he fits the affective core described by Hare's PCL-R: superficial charm, simulated affect, total absence of empathy and of guilt.

His criminal mechanism is listening. Doma does not hunt by force: he comforts. He gathers broken women, offers them paradise and meaning, lets them weep, and then eats them. That sequence —instrumental care followed by predation— is what separates psychopathy from simple sadism: affect is not missing as a capacity to perform, it is missing as an experience. Doma knows perfectly well which face to wear. His case file sums him up in a line he himself delivers with almost childlike bewilderment: he never felt anything, though he should have.

It matters to say this precisely: the emptiness does not absolve. Doma understands perfectly well that what he does causes harm —that is why he hides it behind a temple, a rite and a smile— and chooses to do it anyway. The absence of empathy explains why it costs him nothing; it does not explain why he does it. Between not feeling and devouring there is a distance that can only be crossed by deciding, and Doma crossed it for centuries, daily, methodically.

// Upper Moon ThreeAkaza: unprocessed grief and general strain

Akaza is the villain who most divides the Infinity Castle's audience, and with reason. He was Hakuji: a boy who stole to pay for his father's medicine, who watched that father hang himself to stop being a burden, who found a master and a sick fiancée, and who came home one day to find them poisoned by a rival dojo. He beat sixty-seven men to death with his fists that night. Muzan found him right there. kriminis files him under Agnew's general strain theory (1992): the accumulated loss of valued stimuli and presence of noxious stimuli produces negative affect —anger, above all— that pushes toward delinquent conduct.

What makes Akaza a textbook case is not the tragedy but what he did with it: nothing. He let Muzan erase his memories and turned his grief into doctrine. His obsession with strength —his ritual contempt for «the weak», his insistence that every worthy rival become a demon— is unprocessed grief converted into ideology. If the weak deserve to die, then his fiancée was not murdered: she was selected. His case file describes him as wronged, obsessed and martial, and that order is exactly his biography.

General strain, moreover, is the theory that best exposes the trap. Agnew never claimed that pain produces crime: he claimed that it produces negative affect, and that negative affect increases the probability of delinquent responses among many other possible ones. Millions of people lose their father, their master and the person they love, and kill no one. Akaza had a colossal pain and an entire century to do something else with it. He chose the fist.

// Upper Moon FourNakime: functional obedience and the castle's architecture

Nakime is the easiest villain to underestimate and the most decisive of the arc, because she is the castle. With each stroke of her biwa she rearranges the rooms, transports bodies, separates allies and places each slayer in front of the demon that best suits Muzan. She does not fight, does not enjoy, does not hate: she executes. kriminis files her under routine activity theory, and it is a deliberate choice: Nakime is not a motivated offender, she is the one who manufactures the convergence of offender and target by removing the guardian.

Her criminological profile is one of functional obedience, and that is why she is the most unsettling figure in the castle. The statistics in her case file portray her: high intelligence, moderate violence, empathy near zero, low manipulation. She needs no cruelty because she touches no one. She is the bureaucracy of harm: the figure who makes the slaughter possible without taking part in any of it, and who, if asked, would answer that she was only moving rooms. Criminology knows that role well outside fiction, and it knows that distance from the blow does not erase responsibility for the blow.

// The rest of the catalogueKaigaku, Gyutaro, Daki, Gyokko, Enmu: the other faults

The castle inherits a cast. Kaigaku, the Upper Moon Six who fills the gap left by the previous siblings, repeats Kokushibo's pattern in miniature: Zenitsu's fellow disciple under the same master, more gifted and always in the shadow, terrified of dying with nothing. His case file also classifies him under relative deprivation, and his betrayal drove master Jigoro Kuwajima to seppuku. Seen this way, the inner circle holds two envious men in a chain: the brother and the disciple.

The predecessors complete the map. Gyutaro and Daki came from the worst district in the world —theirs, literally— and their files record it: Gyutaro's file under social disorganization, Shaw and McKay's theory about neighborhoods where informal control collapses; Daki's under cultural criminology, beauty as the only available capital and then as a weapon. Gyokko, by contrast, has no social mitigation whatsoever: his case file places him under the criminal personality, the grandiose artist who turns bodies into vases.

And then there is Enmu, the Lower Moon One of the Mugen Train, who anticipates the castle in miniature: he too built an enclosed space —a moving train, a hundred sleeping passengers— where the guardian could not reach. His case file classifies him, like Nakime's, under routine activity theory. That is no coincidence: the train and the castle are the same idea at different scales. Muzan does not only recruit predators; he designs the places where predation comes cheap.

// The crackThe flashback explains the origin of the harm, it does not cancel the bill

Here is the problem that makes Demon Slayer criminologically interesting rather than merely a sword spectacle. The series has a fixed device: it gives its demons their backstory at the exact moment of their death. As the body crumbles into ash, up come the childhood, the illness, the hunger, the humiliation. It is beautiful and it is dangerous. Beautiful because it restores humanity to someone who had lost it; dangerous because it arrives precisely when the viewer is most emotionally vulnerable and least inclined to keep accounts. Understanding why Akaza broke does not bring Rengoku back. The story's compassion is not an acquittal.

But the opposite edge cuts just as deep, and kriminis does not settle there either. Refusing to look at the backstory —staying with «they were monsters», «they were born that way», «there is nothing to understand»— is exactly what prevents understanding anything. If Kokushibo is a monster by nature, fraternal envy teaches nobody anything; if Akaza is pure evil, unprocessed grief stops being a risk factor one can intervene on in the real world. Prevention lives entirely on the side of explanation: you can only interrupt what you comprehend.