Why did Jigoro Kuwajima commit seppuku in Demon Slayer? Explained

Modified Feb 05, 2025 19:30 GMT

Demon Slayer and why did Jigoro Kuwajima commit seppuku (Image via Ufotable).

Demon Slayer fans who have yet to read the manga and have only seen the anime often ask "Why did Jigoro Kuwajima commit seppuku?". This is because of his steadfast and determined personality in the flashback where he is seen training Zenitsu Agatsuma. However, the reason he took his own life was because of a major event that happened during the Infinity Castle arc and is related to a character named Kaigaku.

Jigoro Kuwajima committed seppuku because his student Kaigaku betrayed the Demon Slayer Corp and became one of the Upper Moon demons serving Muzan Kibutsuji, with the former Thunder Hashira feeling that he failed as a master. His death was a shocking moment for his other student, Zenitsu, and prompted him to overcome his fears to defeat Kaigaku in the final arc of the story.

Disclaimer: This article contains spoilers for the series. Any opinion expressed here belongs to the author and not Sportskeeda as a publication.

Jigoro's actions, explained

Zenitsu and Kaigaku, Jigoro's students, as seen in the anime (Image via Ufotable).

Jigoro Kuwajima was the former Thunder Hashira and eventually retired as he grew older, mostly focusing on training younger generations on the art of the blade. That is how he met one of the main characters of the series, Zenitsu Agatsuma, and became his mentor, helping him master the first of the Thunder Breathing Forms.

There was another student of Jigoro's who was eventually featured in the story, that being Kaigaku, who was a former friend of Zenitsu and someone who eventually became one of Muzan's demons.

He did this after becoming a member of the Corp and surrendering when facing the first Upper Moon, Kokushibo, in an effort to save his life.

This brought great shame to Jigoro and he chose to commit seppuku because he felt he failed as a teacher.

Zenitsu was informed of the passing of his mentor during the Hashira Training arc, with details that his death was slow and painful because no one else was strong enough to cut his neck in one swing.

How Zenitsu avenged his master in Demon Slayer

Zenitsu defeating Kaigaku in the manga (Image via Shueisha).

While a lot of Demon Slayer fans might ask the question "Why did Jigoro Kuwajima commit seppuku?", the ramifications of this event are perhaps even more important.

While Zenitsu always struggled massively with his own fears and insecurities, to the point he could only contribute in combat while asleep, the death of Jigoro pushed him to overcome his flaws and become a much stronger fighter.

That is because Zenitsu knew that Kaigaku not only betrayed their people and their teacher but also humanity as a whole since he chose to become a demon only for survival.

This is perfectly shown when the two students face each other during the Infinity Castle arc in a decisive battle and Zenitsu gets the upper hand, taking the life of the former human in the process and avenging his master.

Final thoughts

"Why did Jigoro Kuwajima commit seppuku?" might be one of the smallest and yet more poignant questions in Demon Slayer when considering that the former Thunder Hashira took his own life out of shame for Kaigaku's betrayal.

All of this played a big role in Zenitsu's character arc during the tail end of the story as he managed to avenge his master.

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Edited by Prem Deshpande