Warning: The following contains SPOILERS for Demon Slayer: Mugen TrainKyojuro Rengoku’s death was the heartbreaking climax of Demon Slayer: Mugen Train — but it was a death that had to happen. For both his and Tanjiro’s characterization, as well as the plot of the Demon Slayer series, Rengoku had to make the ultimate sacrifice. His death leaves a major hole in the Demon Slayer Corps, but it serves to propel the storyline and the young demon slayers forward. But why did this fan-favorite have to die?
As the Flame Hashira, Kyojuro Rengoku is one of the strongest members of Demon Slayer‘s core team. After years of dedicating himself to his craft, Rengoku worked his way to one of the most revered positions within the Corps, possessing incredible willpower and almost unbeatable swordsmanship. When the team needed a Hashira to lead Tanjiro, Zenitsu, Inosuke, and Nezuko in defeating the demon of the Mugen train, Rengoku was an obvious choice.
How Rengoku Died in Demon Slayer: Mugen Train
Rengoku’s performance against the demons on the Mugen train in the Demon Slayer movie was impressive enough to draw admiration from even Inosuke, and Rengoku ensured that not one of the 200 passengers died. Unfortunately, Rengoku succumbed to Akaza, the Upper Rank Three demon, after initially almost defeating him. While this death is undoubtedly one of Demon Slayer‘s most tragic, it also happens for some crucial and impactful reasons.
Demon Slayer’s Rengoku Had to Die to Motivate Tanjiro
It was a heartbreaking moment, but Rengoku’s sacrifice in Demon Slayer made sense both for his character and for the movie’s storyline. In Rengoku’s mind, he is nothing more than a human who has worked hard to gain his abilities; he’s nothing special. He does see something special in Tanjiro, however, which is why he would rather risk his own death than Tanjiro’s. His death serves as a motivation for the young slayer; Tanjro greatly admires Rengoku’s abilities and is even brought to tears when Akaza deems Rengoku the loser in their encounter. Rengoku’s death gives Tanjiro something to strive for — especially when the Flame Hashira announces the faith he has in Tanjiro and his acceptance of Nezuko.
Rengoku was arguably the strongest Demon Slayer Hashira at the time of his death. He was devoted to his position within the Demon Slayer corps as his mother taught him as a young child that the purpose of his strength was to protect others. Mugen Train shows he lived by that creed until his death. He sacrificed himself to ensure that no innocent died and he met his goal. Equally as important, Rengoku’s mother also taught him that his strength must never be used to cause harm, which was why he was able to deny the temptation of becoming a demon. His willpower made Rengoku a force to be reckoned with; he almost killed an Upper Rank demon single-handedly. This power would have made Rengoku a serious threat later in the series, which is why he serves the storyline better by dying in Mugen Train. Not only does his death give Tanjiro a power level to strive for, it also establishes just how much of a threat the demons are.
Rengoku’s death also served to add an emotional touch to Demon Slayer: Mugen Train. The happier dreams of the slayers gave audiences a few warm, wholesome moments right before Rengoku’s death broke their hearts. His character started as more of a comedic foil to the plot, but his death allowed the movie to delve into the seriousness of his background. He may have seemed all brawn on the outside, but Rengoku had some serious brains hiding beneath. His beautiful outlook on life, death, and their purpose in the fight against demons are all lessons the young slayers carry with them from Demon Slayer: Mugen Train into Demon Slayer season 2 and beyond.
Rengoku’s Death in Demon Slayer Established An Important Series Tenet
While Demon Slayer follows many shonen tropes, its emphasis on death sets it apart. Almost every main character in the series has a big death in their background that motivates them. In addition, Tanjiro’s willingness to kill the series’ sympathetic villains sets him apart from many other shonen heroes who prefer non-lethal takedowns. Both of those core elements are established in Demon Slayer’s first season, but it isn’t until Mugen Train that the series really establishes death as a very real and tangible threat for powerful heroes. Demon Slayer has a higher death count for its heroes than most other shonen series and that begins with Rengoku.
Rengoku’s Death Sets Up Later Demon Slayer Seasons
Rengoku’s death will shape the younger slayers for the series’ entire shelf life. As the first Hashira that Demon Slayer‘s young protagonists officially partner with, Rengoku plays a key role in Tanjiro, Zenitsu, and Inosuke’s development as warriors and as people. Muzan Kibutsuji’s awful power in Demon Slayer is an ongoing threat that looms over every Demon Slayer season, and Rengoku’s death is one moment where it becomes abundantly clear. Likewise, his death forces them to mature suddenly as they realize the full extent of the dangers demons pose to the world.
As Tanjiro and his friends fight alongside Sound Hashira Tengen Uzui in Demon Slayer season 2’s Entertainment District Arc, they are even more painfully aware of how high the stakes are, having seen someone as powerful as Rengoku die fighting an Upper Rank demon. This mentality carries over again into Demon Slayer season 3 as the young slayers get to know the Mist and Love Hashiras, Muichiro Tokito and Mitsuri Kanroji. In this way, Kyojuro Rengoku’s death in Demon Slayer: Mugen Train continues to be a source of inspiration and motivation even into the series’ later seasons.