Michikatsu Tsugikuni was, by any reasonable measure, an exceptional man. Born in the feudal Japan of Demon Slayer, he mastered the sword until he became one of the finest demon hunters of his generation. But Michikatsu had a twin: Yoriichi, the most talented swordsman who ever lived, the one who created Sun Breathing and whom the demon king himself feared above all else. And against that light, Michikatsu's excellence looked like dusk. Hence his demon name: Kokushibo, Upper Moon One, Muzan's right hand. For relative deprivation, his story is a textbook case: not that of a weak man who envies the strong, but that of an extraordinary man who simply had the misfortune to be born beside the one being with whom he could not compete.
// The theoryIt's not what you lack: it's who you look at
Relative deprivation was born in an improbable place —the army—. In The American Soldier (1949), Samuel Stouffer found a paradox: soldiers in the branches with more promotions felt more frustrated, because they compared their lot with that of so many promoted comrades. Satisfaction depended not on objective reality but on the reference group. The British sociologist W. G. Runciman (1966) formalized the idea and distinguished egoistic deprivation —me against another like me— from fraternal deprivation —my group against another group—. And Ted Robert Gurr, in Why Men Rebel (1970), carried the concept into violence: what pushes people to rebel is not misery but the gap between expectations and achievements, the distance between what one believes one deserves and what one attains. Kokushibo is egoistic deprivation in its purest form. His reference group was not a distant rival or a social class: it was his own twin brother, the perfect mirror. They had the same face, the same blood, the same age. And yet Yoriichi was born with what was denied to Michikatsu. That equal starting point is what makes the wound unbearable: the closer the object of comparison, the wider the gap feels.
The gap is measured against the closest
Relative deprivation is not ignited by just any comparison, but by the one we feel is legitimate: we compare ourselves with those who resemble us, with those who started from the same point we did. That is why Kokushibo's grievance is so corrosive. A villager does not envy an emperor —he is too far away to serve as a yardstick—, but a twin does envy his twin, because they share the ground from which one rose and the other did not. Michikatsu was not mediocre: measured against the rest of the world, he was a prodigy. But he did not measure himself against the rest of the world. He measured himself against Yoriichi, and against that impossible standard his colossal talent was reduced to insufficiency. The theory explains it with clinical precision: satisfaction is a fraction whose numerator is what you achieve and whose denominator is what you expect —and Michikatsu spent his life placing in the denominator the most gifted person in history—. No figure of achievement, however high, could yield a quotient that satisfied him. That is the trap: when you choose the wrong reference group, even excellence is experienced as defeat.
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// The subjectEternity as an attempt to catch up with his brother
What is revealing about Kokushibo is what for he wanted power. He sought neither wealth, nor rule, nor even cruelty for cruelty's sake like other demons. He sought strength and, above all, time: he agreed to become a demon because mortality would rob him of the chance to keep improving, to finally close the distance. Eternity, for him, was an extension in the race against his brother. And there lies the irony the theory illuminates: for centuries he trained, killed and perfected himself, developed his own Moon Breathing and a demon-mark technique that astonishes his enemies —and even so, at the moment of his defeat, what emerges is not pride in what he achieved, but the child who always wanted his brother to look at him with admiration—. The comparative grievance is never sated because it does not depend on achievement but on the perceived gap; and the gap, when the referent is Yoriichi, never closes. Kokushibo spent four hundred years pursuing an equality that not even immortality could grant him. He forged an enormous strength and discovered, too late, that no amount of strength answered the question that really drove him —why he was not the chosen one—.
Kokushibo
// The crackExplaining envy is not signing off on its victims
The crack with Kokushibo is tempting and must be named. Relative deprivation explains the fuel —the comparative grievance, the brother's shadow, the gap that never closes—, but it does not dictate the outcome. The vast majority of those who carry the frustration of feeling eclipsed do not kill anyone; they live with their envy, sublimate it, transform it or simply endure it. The theory itself acknowledges this as its most honest limit: between the grievance and the crime there is an abyss that comparison alone does not bridge, one that depends on how each person copes and on the opportunities they choose. Michikatsu chose. He chose to accept Muzan's offer, he chose to feed on human beings, he chose centuries of murders that envy describes but does not absolve. There is a moral leap between «I always felt like the second one» and «I devoured countless people to last long enough to surpass my brother», and no grievance, however real, bridges that abyss.
It is also worth not romanticizing comparison as if it were destiny. The parallel with other villains of envy —Loki eternally measuring himself against Thor, Salieri against Mozart— is tempting and partly fair: they all share that egoistic deprivation of the second who cannot bear being second. But Kokushibo's own brother is the counterexample that dismantles the alibi. Yoriichi had the talent and also the loss, the isolation, the burden of being different; and he did not become a demon. The difference between the twins was not what life gave them, but what each one did with the gap. To explain why Michikatsu felt insufficient is to read a real wound; to turn that wound into an excuse for his crimes is to betray those who died so that he could keep existing. To explain is not to exonerate.
Watch the denominator, not just the numerator
Kokushibo matters because he dismantles a comfortable intuition: that only those who lack feel resentment. He had almost everything —talent, recognition, a life of achievements— and yet he consumed himself, because relative deprivation is not cured by accumulating achievements but by changing the yardstick with which one measures oneself. The lesson transcends fiction. In the society of the permanent shop window, where social media offers us at every instant an edited version of others' lives, Kokushibo's mechanism has become an everyday matter: we compare ourselves endlessly with the most gifted, the richest, the most admired, and even abundance is experienced as lack. Comparative criminology confirms it on a large scale —inequality predicts violence better than average poverty—, because what hurts is not what is missing but the visible distance from those who have more. Kokushibo warns us that the enemy is rarely what we do not have: it is the impossible denominator we choose to measure ourselves by, and the inability to forgive ourselves for not reaching it.
Three key takeaways
- Kokushibo embodies relative deprivation (Stouffer 1949; Runciman 1966; Gurr 1970): he was not weak, he was extraordinary, but measured against his twin brother Yoriichi —the most talented swordsman in history— he always felt insufficient. The wound is not the lack, but the comparison.
- It is pure egoistic deprivation: the closer the referent, the wider the gap. Michikatsu sought strength and eternity not out of ambition, but to close a distance that not even four centuries of power could close, because the grievance depends not on achievement but on who one looks at.
- To explain is not to exonerate. The theory describes the fuel of envy, but not the outcome: most of the eclipsed do not kill. Kokushibo chose the demon and centuries of crimes. His own brother, with the same life, did not. Remembrance is for the victims.
Sources · further reading
- Stouffer, S. A. et al. (1949). The American Soldier. Princeton University Press.
- Runciman, W. G. (1966). Relative Deprivation and Social Justice. Routledge & Kegan Paul.
- Gurr, T. R. (1970). Why Men Rebel. Princeton University Press.
- Wilkinson, R. & Pickett, K. (2009). The Spirit Level. Allen Lane.
Case-file questionsFrequently asked questions
¿Quién es Kokushibo?
Kokushibo («Michikatsu Tsugikuni») es un villano de Demon Slayer, analizado en KRIMINIS con la lente de la criminología. He wasn't weak: he was one of the finest swordsmen of his age.
¿Por qué Kokushibo (Michikatsu Tsugikuni) se convierte en villano?
Kokushibo and relative deprivation: how envy of another's talent —that of a prodigious brother— turns an extraordinary samurai into a demon who spends centuries chasing a strength that never makes him his brother's equal.
¿Qué teoría criminológica explica a Kokushibo?
El caso de Kokushibo se analiza desde la Privación relativa. Relative deprivation (Stouffer, Runciman, Gurr) holds that frustration is born not of absolute lack but of comparison: the distance between what one achieves and what one believes one deserves when looking at another who has more. Kokushibo, Upper Moon One of Demon Slayer, was born Michikatsu Tsugikuni, elder twin brother of Yoriichi, the most talented swordsman in history. Extraordinary by any measuring stick, he always felt insufficient before the one person with whom he should never have compared himself. He became a demon in pursuit of a strength and an eternity that never made him his brother's equal.
