Infinity Castle’ Cements This Beloved Character as the Anime Series’ Best

Editor’s Note: The following contains spoilers for Demon Slayer: Kimetsu no Yaiba Infinity Castle.

The true star of the new theatrical Demon Slayer: Kimetsu no Yaiba movie, Demon Slayer: Kimetsu no Yaiba Infinity Castle, is none other than Zenitsu Agatsuma (Hiro Shimono/Aleks Le). Infinity Castle stands out as Zenitsu’s finest hour as he confronts his former sword brother, Kaigaku (Yoshimasa Hosoya/Alejandro Saab), in a deadly battle. Throughout the Demon Slayer saga, Zenitsu came off as a somewhat polarizing character, with some disliking his comedic antics and buffoonish attitude. However, Infinity Castle fulfills the tease of the show’s final season, allowing Zenitsu to put aside his goofy behavior, unlock his true potential, and prove his worth as a member of the Demon Slayer Corps. It’s time to explore how Infinity Castle finally unlocked Zenitsu’s confidence and cemented him as the saga’s best character!

Zenitsu Finally Gets Serious in ‘Demon Slayer: Kimetsu no Yaiba’

During Season 4, Episode 7 of Demon Slayer, “Stone Hashira Gyomei Himejima,” Zenitsu receives a message from his Kasugai sparrow, Chuntaro, that prompts a significant change in attitude for the character. When Tanjiro Kamado (Natsuki Hanae/Zach Aguilar) visits his close friend, he quickly notices that Zenitsu is acting differently and no longer exhibiting his lively personality, making Tanjiro very worried. In the next episode, the Season 4 finale, “The Hashira Unite,” Zenitsu is last seen falling through the Infinity Castle, as the demon lord, Muzan Kibutsuji (Toshihiko Seki/Greg Chun), seeks to entrap all his enemies and eliminate them in one fell swoop. However, during this short moment, Zentisu opens his eyes and grasps his katana, no longer scared, crying, or screaming for his life. In fact, Zenitsu appeared eerily calm and serious, which is quite unlike the teenage Demon Slayer corpsman. He was “locked in,” as the kids say.

The final moments of “The Hashira Unite” lead right into Infinity Castle, showcasing Zenitsu confronting his former brother-in-arms within Muzan’s terrifying domain. Zenitsu’s battle with Kaigaku finally offers insight into the letter the young man recently received from Chuntaro. Zenitsu’s beloved trainer and mentor, Jigoro Kuwajima (Shigeru Chiba/John DeMita), committed seppuku to atone for the shame of Kaigaku’s betrayal of the Demon Slayer Corps. Both Zenitsu and Kaigaku were Jigoro’s disciples, but Kaigaku accepted an offer from Muzan’s chief lieutenant, Kokushibo (Ryotaro Okiayu/Jonah Scott), to become a demon and join Muzan’s Upper Ranks. Zenitsu loved Jigoro like family, affectionately referring to his teacher as “Gramps.” The anger and rage over Jigoro’s death betrayal provoked Zenitsu to transform, unleashing his true skills and abilities, putting his crybaby antics to bed.

Zenitsu Surpasses His Master in ‘Infinity Castle’

During Zenitsu’s battle with Kaigaku, flashbacks depict their tutelage under Jigoro, formerly an elite Hashira of the Demon Slayer Corps. Zenitsu always appeared to be a screw-up and inferior fighter, failing to master past the first form of Jigoro’s six Thunder Breathing techniques. However, despite being the star pupil, Kaigaku could only master the other five forms of Thunder Breathing, branding Kaigaku and Zenitsu as failures. However, previous episodes of Demon Slayer showcased that Zenitsu, despite appearing weak, easily frightened, incompetent, and idiotic, was capable of unlocking a hidden battle sense. When Zenitsu falls asleep, he suddenly becomes a highly skilled and deadly swordsman, an ability that helped him survive multiple deadly encounters with demons throughout the series. Enraged by Kaigaku’s actions, Zenitsu finally springs into battle, fully awake and motivated, and utilizes his full combat abilities.

What is interesting about the battle is that Kaigaku derides his former comrade, utilizing criticisms that sound remarkably similar to how fans of the franchise would often complain about Zenitsu. With that in mind, it’s exciting to see Zenitsu confront and overcome an enemy with a shared backstory who looks down upon him. Despite Zenitsu’s failure to grasp his sensei’s other Thunder Breathing forms, Zenitsu ultimately surpasses his master, creating a brand-new seventh form of Thunder Breathing. Zenitsu ultimately defeats his former sword brother — not by mastering all the original forms of Thunder Breathing, but through creating his own unique version of it. Zenitsu proves the difference between being a good swordsman and a master: To become a true master, you must create something beyond your predecessor. Witnessing Zenitsu overcome such a formidable enemy by creating a new form of Thunder Breathing saw fans cheering out loud in theaters across the globe.

Zenitsu Shares an Emotional Final Farewell in ‘Infinity Castle’

After defeating Kaigaku, Zenitsu appeared to be on the brink of death from wounds he suffered in the fight. During his delirious dream-like state, he encounters his teacher, Jigoro, one last time. An anguished Zenitsu apologizes to his master, but Jigoro, his spirit now at peace, simply tells his disciple, “Zenitsu, you are my pride and joy,” demonstrating his unconditional love for his student, his feelings reaching Zenitsu from beyond the grave. The deeply spiritual moment showcases how Jigoro and Zenitsu’s relationship was more like that of a kindly grandfather and grandson.

Demon Slayer is an incredible series full of emotional moments and absolutely bittersweet tearjerkers, but few moments come close to the emotions of Jigoro sharing his overwhelming love for Zenitsu. For once, the buffoonish failure gets his opportunity to shine, and Zenitsu rises to the occasion. Demon Slayer depicts Zenitsu as the ultimate underdog, and many of his devoted fans likely see themselves in the character, which makes his crowning achievement in Infinity Castle even more rewarding. Zenitsu achieves his full abilities without having to fall asleep, sheds his usual crybaby antics, finds his courage, and shows that even a failure can reach true greatness. There is a Zenitsu in all of us, proving that he is the greatest character created by the original author, Koyoharu Gotouge.