Death is inevitable in the world of kimetsu no yaiba as human-slayers battle flesh-eating demons to save the human race.
Even the Hashiras who are regarded as the strongest in the demon slayer corps are not exempt from this cruel faith, as evidenced by the demise of the infamous Flame Hashira Kyojuro Rengoku in the Mugen train movie.
The death of Rengoku was a tough one for the majority of the fans, as many questioned the reason for his death and whether it was really necessary.
Flame Hashira Rengoku’s death was necessary to Inject the reality that the hashiras aren’t invincible, show the power difference between the hashiras and upper moon demons, influence Tanjiro’s character development, and ultimately contribute to the future plot of the series.
How Did Flame Hashira Rengoku Die?
Flame Hasira Kyojuro Rengoku died in the Mugen train arc, in a battle with an upper-rank three demon, Akaza. He fought bravely to protect Tanjiro, Nezuko, Inosuke, Zenitsu, and other passengers on the train before ultimately succumbing to his fatal wounds.
Rengoku may have succumbed to his wounds after the battle, but he successfully kept Akaza at bay from other people until dawn.
Tanjiro declared Rengoku the winner of the battle since he never behaved cowardly and fulfilled all of his obligations throughout the battle, whilst Akaza fled (due to sunrise).
Regardless of the outcome, Fans still wonder if Rengoku would have triumphed in a different scenario. i.e., not having to protect anyone.
The sad truth is that Rengoku would still experience the same fate even if situations changed.
Akaza is just that strong, his blood demon art and tremendous regenerative abilities set him apart from other demons.
5 Major Reasons Why Flame Hashira Rengoku Had to Die
1. To Inject the Reality That the Hashira Aren’t Invincible
Even though the hashiras are the strongest of the demon corps, they are mortals with human blood coursing through them.
No matter how strong they are, they aren’t immortal and could all ultimately taste death.
2. To Show the Power Difference Between the Hashira’s And the Upper Moon Demons
There’s the average demon and then the twelve kizuki/ demon moons.
The twelve kizuki are the most powerful demons in the series, handpicked by the demon king, Muzan Kibutsuji.
By ingesting his blood, they potentially acquire extraordinary abilities, which grant them blood demon art, cutting-edge combat skills, tremendous regenerative abilities, and many other abilities.
The twelve kizuki are divided into two groups; the six upper ranks and six lower ranks.
Akaza is the first upper moon demon to appear in the franchise. He debuted in the Mugen train arc, where he faced off with the Flame Hashira Kyojuro Rengoku.
This battle which ultimately led to the death of Flame Hashira Rengoku served as a way to introduce the upper moons and demonstrate their tremendous strength.
3. To Influence Tanjiro’s Character Development
Like most popular shonen anime, the death of a significant character is mostly used to influence the protagonist’s development.
Take for instance the passing of Jiraiya from Naruto, Ace from One Piece, Fujimoto from Blue Exorcist, and so on.
These deaths spur the protagonist to push beyond their limit and become stronger.
In Tanjiro’s case, Rengoku’s passing serves as motivation for him to exceed his limit and become a powerful hashira.
4. To Contribute to The Future Plot of The Series
The death of a major character will no doubt change the course and stakes of a plot.
In demon slayer’s case, we speculate that Rengoku’s passing was to extend Tanjiro’s journey to master the hinokami kagura (sun breathing style).
The sun-breathing style and Rengoku’s fire-breathing style are closely connected. And with him mentoring Tanjiro, it won’t be long before he unlocks the secrets of the sun breathing technique, which will make it slightly easier to get rid of Muzan.
By eliminating Rengoku, Tanjiro would have to look for alternative methods of mastering the sun breathing technique, extending and intensifying the story.
5. To Give the Movie the Perfect Ending
The Mugen train movie could have ended with no death and would still be fine.
There is, however, a certain emotion associated with shows that have a bittersweet ending, where the hero saves the day but loses their life in the process.
Sometimes, sacrificing a character or two are all that it takes to complete a master story.
Can Another Hashira Defeat Akaza? (Spoiler!)
This might seem shocking but no Hashira is strong enough to defeat Akaza since he won’t die, even after decapitation.
Akaza faced off against hashira-level Tanjiro Kamado and Giyu Tomioka in the Infinity Castle arc in the manga.
It took them everything they had just to decapitate Akaza, but to their surprise, his headless body continued to battle while his head slowly regenerated.
It would have been game over for both Tanjiro and Giyu had Akaza not remembered his human past and chosen to kill himself out of shame for the monster he’d become.
The only method to kill Akaza since he can’t be decapitated is to expose him to sunlight, which we would say is not an easy task.
Who Will Become the Next Flame Hashira? (Spoiler!)
Sadly, there would be no one to succeed Rengoku as the next flame hashira. His younger brother, Senjuro, would have been the ideal candidate, but he is not even half hashira-level-strong and his nichirin sword never changed color.
That leaves us to consider Tanjiro since he has a history with Rengoku and their breathing style are somewhat related.
However, Tanjiro didn’t receive the Hashira title in the manga despite completing the necessary training.
This is because the ultimate battle with Muzan had already begun by the time he was strong enough to become an Hashira.
Moreover, The Demon Slayer Corps disbanded after defeating Muzan, as they have no reason to exist anymore.