The new Demon Slayer movie, officially titled Infinity Castle – Part 1: Akaza Returns, is generating significant buzz, and that excitement is likely to continue! As the 98% RT anime dominates the box office, many fans have become familiar with Tanjiro Kamado’s heartfelt journey. However, while Tanjiro is the heart of the franchise and the Hashira serve as its backbone, one character who is equally important yet often overlooked is Zenitsu Agatsuma.
Despite being a main character, Zenitsu, with his yellow haori and matching Nichirin sword, is frequently perceived as annoying and dismissed as comic relief or a coward. Nevertheless, his character develops one of the most powerful abilities in Demon Slayer — his unique Thunder Breathing Form — and he delivers some of the franchise’s most memorable battles, especially in Infinity Castle. Fans who may have underestimated Zenitsu early on can no longer overlook him as he takes on a defining role in the new movie, reshaping his entire journey and highlighting his utmost importance in the anime’s foundation.
Zenitsu Is the Most Relatable Hero in Demon Slayer
Where Tanjiro is selfless and courageous with a heart full of gold, Zenitsu is… well, terrified! Fans are introduced to this character in the “Final Selection” episode of Demon Slayer, but it’s not until the end of “Together Forever” that we see his trademark traits. In the episode’s final moments, leading into “Tsuzumi Mansion,” Zenitsu clings desperately to a young girl’s hand, begging her to marry him because he believes he won’t live long as a demon slayer. This immediately made him a walking joke among many viewers, who failed to see beyond his fearful exterior without considering that Zenitsu’s response to threatening situations is pretty much how a normal human would react.
Looking at Zenitsu’s backstory, it doesn’t start off as a grand tragedy like some Demon Slayer characters. Before joining the Corps, he was insecure, directionless, and even fell into significant debt. Fortunately, his life didn’t end up a complete disaster thanks to Jigoro Kuwajima. Jigoro was the former Thunder Hashira who took Zenitsu in as a student, seeing potential in him even when he didn’t believe in himself and struggled to master anything beyond the First Form of Thunder Breathing. At least, the “scaredy-cat” was able to perfect this technique exceptionally well, proving he was not a lost cause after all.
All these events led up to Zenitsu becoming a demon slayer, which, as viewers already know, wasn’t by choice. He didn’t volunteer to become a hero out of bravery; in fact, he never truly wanted to risk his life fighting demons but adhered to it out of duty to honor Jigoro. Thus, Zenitsu may not be the fearless warrior archetype, but his journey symbolizes what it feels like to live with anxiety and constant doubt about life and death. Beneath all that fear lies a deep desire to protect those he cares about, especially his friends — an instinct that gradually evolves into his true motivation for fighting.
Zenitsu Might Be Demon Slayer’s Most Underrated Fighter
When it comes to battles, Zenitsu’s tantrums surprise no one, making him easily dismissed as dead weight. However, that’s precisely why his transformation catches everyone off guard every single time. The moment he falls unconscious or reaches a breaking point during combat, his body takes over and the petrified Zenitsu is no longer in control.
What makes him an even more admirable demon slayer is his ability to hone his First Form of Thunder Breathing. The technique may seem simple compared to other Breathing Styles, but Zenitsu’s capacity to wield it with extreme speed and accuracy makes it deadly and comparable to a lightning strike. While other demon slayers might prolong a fight, Zenitsu ends it in an instant — which is incredibly impressive for a character everyone underestimates.
His ability is highlighted throughout Demon Slayer, showcasing just how lethal a single move can be. The very first time we see Zenitsu unleash the First Form, Thunderclap and Flash is in the “The Boar Bares Its Fangs, Zenitsu Sleeps” episode when he instinctively defeats the Tongue Demon inside Tsuzumi Mansion while fast asleep. Fast-forward to the “You Must Master a Single Thing” episode where he finishes off the Spider Demon with a sixfold Thunderclap while performing the technique for the first time. Later in the Entertainment District, he pushes this technique even further against Daki and Gyutaro.
‘Infinity Castle’ Finally Proves Zenitsu’s Worth in the Demon Slayer Franchise
For those who have yet to experience the masterpiece called Infinity Castle, just know that you’ll be amazed by Zenitsu’s performance. The movie finally gives this young hero the spotlight he deserves by placing him into one of the arc’s most emotional and high-stakes battles: a confrontation with Kaigaku. Like Zenitsu, Kaigaku trained under Jigoro before betraying them and allowing Kokushibo, the Upper Rank One demon, to transform him into the new Upper Rank Six demon following Daki and Gyutaro’s deaths. This betrayal led Jigoro to commit seppuku in atonement — something Kaigaku clearly did not regret. In contrast, Zenitsu viewed this betrayal as dishonor upon their master and sought vengeance.
The epic battle isn’t just another demon versus slayer fight — it’s personal. Zenitsu fights not only for his master’s honor but also to prove his own worth. During this confrontation, Zenitsu develops and utilizes the Seventh Form of Thunder Breathing, Flaming Thunder God — a technique entirely of his own creation that ultimately defeats Kaigaku. This moment was pivotal for Zenitsu as he not only triumphed but also established his superiority by surpassing someone who had mastered multiple Thunder Breathing forms through sheer willpower and dedication.
Zenitsu may have entered Demon Slayer as the terrified tag-along, but the Infinity Castle movie establishes him as so much more. Through his journey, we learn that true courage isn’t about being fearless but rather about being terrified yet fighting anyway. This makes him a hero who’s much more human than others, one of the franchise’s most deserving heroes who deserves far more recognition than he receives.
Demon Slayer: Kimetsu no Yaiba – The Movie: Infinity Castle is currently playing in theaters.
