History YMMV / DemonSlayerKimetsuNoYaiba

** Was it actually cowardly of Akaza to [[spoiler:flee from the sunlight after killing Rengoku, or was he fully within his right to flee from his AchillesHeel]]? Fans with a negative opinion of Akaza believe the former, while those with a positive opinion believe the latter.

** Akaza's intense battle with Rengoku and offering [[WeCanRuleTogether the latter to become a demon so that they could advance in the ranks of the Twelve Kizuki together]]. [[spoiler:Ironically, Akaza ends up killing Rengoku.]]

** Creator/MarkWhitten's performance as Rengoku in the English dub of the TV series received a lukewarm reception at first, as it was seen by some as being quite lackluster at that time. When the Mugen Train movie was released in English, his performance noticeably improved and was praised by reviewers as being one of the best for portraying Rengoku in a more complex manner with a wider range of emotions. Some highlights include [[spoiler:his dream sequence with his father and brother near the beginning, his fight scene with Akaza during the climax as well as his final scene with Tanjiro before passing away]].
** The same applies with Creator/ZachAguilar's performance as the main lead Tanjiro. Many fans criticized it as being flat in comparison to Creator/NatsukiHanae. But Mugen Train's English release began to change many people's opinions on it, particularly when Tanjiro yells at Akaza [[spoiler:after he flees from the sun after punching a fatal wound in Rengoku's stomach.]] Many feel like Zach took the criticism to heart, and keeps improving his role.

** Some consider the strong admiration Uzui holds for Rengoku to be this. It's clear he liked and respected the Flame Hashira very much, to the point that he set a standard (saving lives) based on him and wished he could meet it.

* ItWasHisSled: Due to the success of the movie as well as how [[EnsembleDarkHorse beloved of a character]] he is in general, almost everyone knows that [[spoiler:Rengoku dies at the end of the Mugen Train arc]].

** Tanjiro has already been shipped with nearly everyone in the series as of this point in writing, from Zenitsu, Inosuke, Giyu, Genya, Rengoku, Kanao and more.

** [[spoiler:After Rengoku's death at the end of the Mugen Train arc, fans were worried that Tengen was going to meet the same fate, especially with the heavy amounts of damage he suffered at the hands of Gyutaro. However, their fears quickly subsided when Tengen attempting to give his final words became a comical scene of his wives bickering. Sure enough, he survived.]]

** The ninth flame breathing style, ''Rengoku'', obviously didn't really need to be translated, since it's named after its user. However, the Norwegian sub translated it into ''Skjærsild'', a word most commonly translated as "Purgatory", but more accurately translates as "the fire that burns away sin". ''Very'' appropriate for a technique used to kill demons.

** There are multiple fan arts of Gyokko in a human form, which depict him as a attractive if not colorful and slightly effeminate man.

** [[TheDeterminator Akaza]], Upper Rank 3, was born [[NobleDemon Hakuji]] and adopted his SocialDarwinist beliefs after the deaths of his loved ones and becoming a demon under Muzan. Baiting a Hashira into combat, Akaza mortally wounds him to tempt a strong opponent with demonhood, yet respects the man's decision to die human when he refuses. Returning later, Akaza shows his full tactical abilities while facing both hero Tanjiro Kamado and another Hashira simultaneously. Constantly switching maneuvers to keep them on the defensive, Akaza even dies by his own hand, forgoing a chance to kill his opponents to commit suicide and [[TogetherInDeath reunite with his family]].

** Similarly, another RoleSwapAU, that can sometimes overlap with the previous, portrays the Hashira and other humans as demons, while the Twelve Kizuki and other lesser demons become Demon Slayers, with the Upper Ranks in particular being Hashiras.

** You didn't think we'd leave out Nezuko, did you? She looks cute, has endearing love for her siblings, and even after becoming a demon, she doesn't lose her cuteness, regardless of whether she is snarling at someone, crawling into her box, or sleeping, because any given viewer is likely to see her as just as precious as her devoted brother does.

** Was it actually cowardly of Akaza to [[spoiler:flee from the sunlight after killing Renoguku, or was he fully within his right to flee from his AchillesHeel]]? Fans with a negative opinion of Akaza believe the former, while those with a positive opinion believe the latter.

** In a similar vein, Tanjiro's father [[spoiler:knowing how to access the Transparent World]] is given no buildup, though Tanjiro once again taps into his memories and learns to use the ability, allowing him to hold his own against [[spoiler:Akaza, whom he and Giyu were previously outmatched against.]]

** Daki crossed this when she bullied and abused one of her servant girls to suicide; if not then, then it's ''definitely'' when she murdered Omitsu (Kyogoku House's manager) when she confronted her over the matter.

** On a similar note, Genya's was disliked at first due to him being characterized as little more than a [[{{Jerkass}} violent thug]] with unjust [[HairTriggerTemper anger issues]], reminding some of a certain BaseBreakingCharacter of [[Manga/MyHeroAcademia?from=Anime.MyHeroAcademia another anime]]. It would take him getting a DayIntheLimelight episode, and him [[FireForgedFriends developing a genuine friendship with Tanjiro]] for that opinion to change, and he is know one of the most popular characters of the series.

** Giyuu and Shinobu have multiple scenes together and interactions spread throughout the manga, Giyu's canonical spin-off manga, light novels, fanbooks, and databooks. Many fans are vocal about their love for the ship, to the point where much fanart and fanfiction stories of them exist. This was taken further after the second fanbook revealed that both enjoy talking to each other, according to Gyomei's observations, as well as their positive opinions of each other.

** The teenage girl who attempted to destroy Rengoku's spiritual core is usually shipped with Enmu, likely due to being the "ringleader" of the 4 teenaged pawns after Enmu, as she tried to lead the failed assault on Tanjiro when he wakes up.

** [[Characters/DemonSlayerKimetsuNoYaibaKokushibo Kokushibo]], [[Characters/DemonSlayerKimetsuNoYaibaTwelveKizukiUpperRanks Upper Rank]] 1, was born [[TheAce Michikatsu Tsugikuni]] and joined Muzan to stave off death in order to grow more powerful. Almost wiping out the Demon Slayers, the only warrior to ever exceed him in power was his younger twin [[Characters/DemonSlayerKimetsuNoYaibaYoriichiTsugikuni Yoriichi]], whom Kokushibo was never able to fully cease loving. In modern times, Kokushibo is undefeated, killing countless Demon Slayer elites and manipulating some, such as Kaigaku, into becoming demons before casually dominating the battle with his descendant Muichiro Tokito. Engaging the strongest of the [[Characters/DemonSlayerKimetsuNoYaibaHashira Hashira]] and concealing his true power to catch them off guard, Kokushibo takes every chance to show why he is the strongest of the Kizuki.

** [[BigGood Kagaya Ubuyashiki]] is the brilliant leader of the [[Characters/DemonSlayerKimetsuNoYaibaDemonSlayerCorps Demon Slayers Corps]]. A kind man who [[AFatherToHisMen loves his subordinates like his own children]], Kagaya is still willing to go to extremes to see the monstrous [[Characters/DemonSlayerKimetsuNoYaibaMuzanKibutsuji Muzan Kibutsuji]] dead, subjecting the trainees to a potentially deadly selection process where they have to fight captive demons, while also memorizing the names and faces of every single Demon Slayer who dies. A genius planner, Kagaya keeps Muzan and his forces at bay through a complex hiding system to defend his strongholds and sets plans to move and crush the powerful [[Characters/DemonSlayerKimetsuNoYaibaTwelveKizuki Twelve Kizuki]] of the demon forces. Captivating the love of his subordinates with his natural charisma, Kagaya uses himself, his wife and his two eldest daughters as bait for Muzan himself to sacrifice all their lives in an explosion and give the Demon Slayer elites a chance to kill Muzan for good.

** [[Characters/DemonSlayerKimetsuNoYaibaAkaza Akaza]], Upper Rank 3, was born [[{{Determinator}} Hakuji]] and adopted his SocialDarwinist beliefs after the deaths of his loved ones and becoming a demon under Muzan. Baiting a Hashira into combat, Akaza mortally wounds him to tempt a strong opponent with demonhood, yet respects the man's decision to die human when he refuses. Returning later, Akaza shows his full tactical abilities while facing both hero [[Characters/DemonSlayerKimetsuNoYaibaTanjiroKamado Tanjiro Kamado]] and another Hashira simultaneously. Constantly switching maneuvers to keep them on the defensive, Akaza even dies by his own hand, forgoing a chance to kill his opponents to commit suicide and [[TogetherInDeath reunite with his family]].

** In addition, Mitsuri is sometimes shipped with Zohakuten mainly due to the gimmick of the ''Love'' Hashira being in a relationship with the embodiment of Hantengu's ''Hatred''.

** Right before [[spoiler:his death,]] Rengoku tells Tanjiro that he has faith that he'll become the next Hashira. Filled with determination and grief, Tanjiro later vowed to Senjuro that he'll make good on this and one day become a Hashira. Genya also vows that he'll become a Hashira in order to reconcile with his older brother, with Tanjiro giving him words of encouragement. [[spoiler:Unfortunately, Muzan is defeated and the Demon Slayer Corps are disbanded before any of that could come into fruition. Not like it would've mattered, as Genya dies in the Infinity Castle arc and Tanjiro is left with a crippled and emaciated left arm. Even if Tanjiro gets to live a happy life after the final battle, all these promises were ultimately in vain.]]

** While Creator/RayChase as Tengen Uzui and Creator/BrandonMcInnis as Gyutaro were already held in high regard, many fans were especially impressed in the final fight scene they had in the dubbed version of "Never Give Up" finding them to really capture the rage and desperation the two had, as well as being a scene that actually surpasses the original Japanese version. It also helps that Ray Chase cracks his voice while yelling which does even more to sell it.

** [[Characters/DemonSlayerKimetsuNoYaibaMuzanKibutsuji Muzan Kibutsuji]] was born a sickly child in the Ubuyashiki family, but through a doctor's attempts to cure him incidentally became the [[MonsterProgenitor first]] and mightiest demon and grew obsessed with [[ThePerfectionist his own perfection]]. [[TheCorrupter Corrupting]] others into demons by preying on their weakness at their lowest then infecting them using the special properties of his blood, Muzan develops the system where demons [[ToServeMan feed on humans]] en masse for power, leading to countless innocent deaths as he maintains this system for over one thousand years, with his blood poisoning and painfully killing any who so much as utter his name in front of his enemies. Muzan is also personally responsible for killing the mother and siblings of the young hero [[Characters/DemonSlayerKimetsuNoYaibaTanjiroKamado Tanjiro Kamado]], as well as the demonic transformation of his younger sister Nezuko. When encountered, Muzan escapes notice by turning an innocent man into a demon and siccing him on his wife before killing several other humans in a fit of pique when they trouble him. Muzan orders countless humans slaughtered, and when several of [[Characters/DemonSlayerKimetsuNoYaibaTwelveKizuki his top subordinates]], the Lower Ranks, [[YouHaveFailedMe disappoint him]], Muzan [[BadBoss massacres the survivors]], deciding they are too weak to survive. Later attempting to massacre all of the Demon Slayers, [[ThanatosGambit when Muzan knows death is inevitable]], he intends to turn Tanjiro into a demon to kill them in his stead. A sadistic, cowardly sociopath predicating a survivalist society of bloodshed to maintain his own safety, Muzan stands responsible for the most death and suffering in the series.
** [[Recap/DemonSlayerKimetsuNoYaibaMugenTrainArc "Mugen Train" arc]]: [[SoftSpokenSadist Enmu]] is [[Characters/DemonSlayerKimetsuNoYaibaTwelveKizukiLowerRanks Lower Rank]] 1 and a suffering-addicted psychopath. As a human, Enmu claimed to be a doctor, falsely "curing" the dying for his own profit and prestige until being made into a demon by Muzan. [[PsychoSupporter Insanely worshipful of Muzan]], Enmu swiftly kills to climb the ranks of the demons and even survives Muzan's purge of the Lower Ranks by impressing his master with his love of pain and death. Empowered and sent after Tanjiro, Enmu uses [[ForcedSleep his powers over dream and sleep]] to put Tanjiro and his friends into pleasant dreams while tricking humans into entering their dreams to [[MindRape destroy their minds]]. Enmu promises to give train passengers kind dreams, but delights in twisting their dreams into horrific nightmares, and when cornered by Tanjiro opts to fuse with the train itself and try to devour all 200 passengers, gloating how he means to torment his victims before [[ToServeMan he eats them]] to further empower himself.

** Many fics [[https://twitter.com/tsukiakii/status/1167514354943762433 do a role swap where Tanjiro was the one turned into a demon]] while Nezuko was away for whatever reason, and she's the one that becomes a Demon Slayer.

** More of a Memetic Weakling. Tengen wives are sometimes ridiculed for their relative weakness in comparison to their husband, or other demon slayers. Not helped by the fact that their inferiority in strength is pointed out by Makio herself, and Hinatsuru having to rescued by the 3 main slayers after almost being killed by the Upper Six siblings, '''twice'''.

** Genya is thought by some to have asthma or another type of lung disease, mostly because it's a more satisfying explanation for [[spoiler: his inability to use breathing styles [[FanDislikedExplanation than what is provided.]]]]

** Murata, although unlike Haganezuka, it's completely ironic. In-universe, Murata is a purely comic relief character who although not weak, is a rather unimpressive demon-slayer. However, he is jokingly referred to as the most powerful demon slayer either for pure ironic comedy, or in reference to him surviving hellish arcs such as Mount Natagumo and the Infinity Castle, and living towards the end of the story, [[spoiler:pre-timskip that is]]. Especially in a series where non-descript demon slayers are usually nothing more than cheap gore.

* TheyChangedItNowItSucks: Some find Karaku's [[ChildLikeVoice drastic voice difference in the English Dub to be to jarring and not fit his character.]]

** A very small portion of the fandom consider Gyokko and Hantengu's default form to be this, the latter in particular for being able to shrink to a small size, and for coming across as a JerkassWoobie to them. Some fan artists will tone down their grotesque features and draw them a Pokemon-esque chibi style.