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The following article contains massive spoilers for Demon Slayer.
Demon Slayer: Kimetsu no Yaibawill release a new movie in a few weeks, and it is expected to be a massive hit, breaking records and potentially becoming the highest-grossing Japanese movie. Currently, anotherDemon Slayermovie holds this place:Mugen Train.
In fact,Mugen TrainandInfinity Castleare deeply related, and not just because they are part of the same story, but also because the Infinity Castle arc directly addresses events from the Mugen Train arc. A key event from Mugen Train that reshaped the story, particularly Tanjiro’s character, will be deeply important in the new movie: Kyojuro Rengoku’s death.
Why the Mugen Train Arc Is So Important in Demon Slayer
The Mugen Train Arc is one of the best arcs in the story. Many fans even consider itthe second-bestDemon Slayerarc, only behind the Infinity Castle arc (and well ahead of the Sunrise Countdown arc, the final arc of the story). It is not surprising that Mugen Train ranks so well among fans, as this arc basically shaped what came next in the story.
The arc was fully adapted into theMugen Trainmovie, later transformed into the Mugen Train TV Arc (with bonus scenes). Initially, Tanjiro Kamado, Nezuko Kamado, Zenitsu Agatsuma, and Inosuke Hashibira board a train to assist the Flame Hashira Kyojuro Rengoku in tracking and defeating a Lower Rank Demon, Enmu. After a fierce battle, they are able to kill Enmu and defend the passengers on board. However, everything changed once Akaza appeared.
Rengoku Was A Fan-Favorite Character
Rengoku may have died relatively early in the series, but he is a remarkable character and became incredibly popular with the fan base. He is the first Hashira that fans know better, likely partly responsible for driving away the impression that Hashira were just strong warriors who lacked deeper motivation. He was also very charismatic, softening the impression that the Hashira were serious all the time.
Fans were drawn by his uniqueness, and he had both a serious and effusive presence. It’s clear that he has gone through many hardships to become a Hashira, but at the same time, he is incredibly nice and friendly. However, while many fans would rather want Rengoku to live a bit longer, his death was crucial for the story’s development.
Tanjiro Was Deeply Affected by Rengoku’s Death
When Akaza appeared, Tanjiro and Inosuke were already tired and injured, so Rengoku continued the fight mostly alone. While Rengoku was able to inflict considerable damage on Akaza, the demon’s healing abilities were incredibly fast. Akaza actually complimented Rengoku’s abilities and proposed that he should become a demon, which Rengoku fiercely declined. However, in the end, Rengoku was defeated, but not without ensuring that everyone was safe. Because the sun was rising, Akaza fled the scene.
I will fulfill my duty! I won’t let anyone here die!
— Kyojuro Rengoku
Tanjiro tried to help Rengoku, but he was also exhausted. Using his last ounce of strength, Rengoku told him to live with his head held high and also that he would know more about Hinokami Kagura ifhe visited the Rengoku House. Before dying, he stated that he believed in them to become the next generation of Hashira.
When Tanjiro and Inosuke informed the Demon Slayer Corps about Rengoku’s death, everyone was in disbelief. It took a particular toll on Tanjiro, who spent months devastated by his death. At the same time,Rengoku’s death gave both the Corps and Tanjiro the determination to keep on their mission to kill Muzanand destroy all demons once and for all. Tanjiro definitely wouldn’t be the same characterif Rengoku had survived, as his death forced him to mature.
Demon Slayer: Infinity Castle Will Avenge Rengoku
The first movie in theDemon Slayer: Infinity Castle Arctrilogy will feature a long-awaited moment: the final battle between Akaza, Tanjiro, and Giyu Tomioka. Tanjiro will finally havethe chance to avenge Rengoku’s death in the Mugen Train arc and defeat Akaza. Tomioka also has some personal scores to settle with the demon. This will probably be an emotional whirlwind for fans watching the movie.
Demon Slayer: Kimetsu no Yaiba – The Movie: Infinity Castlewill be released in Japan on July 12, 2025, so fans who want to avoid spoilers before going to the theater should take extra care on social media then. The movie will be released in the US and Canada on September 12.
Demon Slayeris available to watch on Crunchyroll andNetflix in the US. The series has been dubbed in English and several other languages.
Demon Slayer
Based on Koyoharu Gotouge’s shonen manga, Demon Slayer: Kimetsu no Yaiba is an action anime set in Japan during the early 20th century. Seeking revenge for the murder of his family while also looking to save his sister, Tanjiro joins the Demon Slayer Corps as they try to eradicate Demons led by Muzan.
