Why did Kaigaku hate Zenitsu in Demon Slayer? Explained

Demon Slayer featured some of its most interesting battles in the Infinity Castle arc. While the series has had thrilling fights in each arc, nothing beats what was shown in the Infinity Castle arc. Demon Slayer reached its zenith in battles and has fights that can be considered the best in anime/manga.

What makes these fights more remarkable is the underlying emotional element behind every sword slash and each fist thrown. One fight that was heavily talked about by fans was the one between Zenitsu, and Upper Ranked Moon Six, Kaigaku. What made this battle so supercharged was the shared history between Kaigaku and Zenitsu.

Kaigaku hated Zenitsu for a plethora of reasons, one of them being former students of the same master. During the battle, Kaigaku repeatedly berated Zenitsu. This led many Demon Slayer fans to ask, “Why did Kaigaku hate Zenitsu?” Here is why Kaigaku hated Zenitsu in Demon Slayer.

Disclaimer: This article reflects the writer’s opinion and may contain spoilers.

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Kaigaku's hatred for Zenitsu, explained

Kaigaku’s evil started from his human days (Image via Ufotable)

The question, “Why did Kaigaku hate Zenitsu?” is obvious. Anyone who comes across the Infinity Castle arc notices how Kaigaku views Zenitsu with disdain.

Kaigaku and Zenitsu were students of the same master, Jigoro Kuwajima, the former Thunder Hashira. Zenitsu heavily struggled during his training as he only managed to master the first form of Thunder Breathing. This was in huge contrast to Kaigaku who mastered every form except the first one. Despite that, Jigoro decided that Kaigaku and Zenitsu would be his joint successors.

This heavily angered Kaigaku who had a superiority complex and didn’t want to share a position with Zenitsu.

Kaigaku’s warped sense of morality also contributes to his hate for Zenitsu. Kaigaku believes the world is ruled by the strong, a belief shared by Akaza, another Upper-Rank Moon. Where Kaigaku and Akaza differ is in honor. Akaza believes in fighting honorably while Kaigaku doesn’t understand the concept of honor.

When he sees the kind nature of Zenitsu, it infuriates him. He can’t grasp the idea of another human who wants to chase power. This is another reason he hates Zenitsu.

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Kaigaku and Zenitsu's relationship in Demon Slayer

Zenitsu eventually surpasses Kaigaku (image via Ufotable)

The relationship between Kaigaku and Zenitsu was a mess during their stints as students of Jigoro. Kaigaku viewed Zenitsu as pathetic and when he saw Zenitsu try to be more familiar with their master, the hate increased.

Zenitsu also hated Kaigaku but still respected him. His respect was due to Kaigaku’s talent and mastery of every other form. Though Zenitsu disliked Kaigaku, he didn’t wish him ill, he hoped to one day fight on equal footing with him.

When Kaigaku and Zenitsu meet in the Infinity Castle arc, the fight is not just between demon and demon slayer. It is a battle of recognition. Zenitsu embodies the will of Jigoro and Kaigaku is the antithesis of that will.

Kaigaku becomes a demon after meeting Upper Moon One, Kokushibo. Once his master hears what Kaigaku has become, he commits Seppuku. This added tension makes the fight between Kaigaku and Zenitsu more dramatic. The fight ends with Zenitsu winning despite Kaigaku knowing more forms of Thunder Breathing.

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Final Thoughts

Kaigaku is a narcissist with a superiority complex that comes out at every turn. His sense of morals is so twisted that he sees no wrong in his actions. He is also one of the few demons in Demon Slayer who doesn’t regret any of his actions while dying.

Kaigaku’s hate for Zenitsu was due to how weak he perceived him to be. If Zenitsu was stronger, Kaigaku would have found a way to sabotage him as he did to Gyomei Himejima. Kaigaku believes in himself more than anything and anyone who goes against that belief is an enemy.

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