Dark And Troubled Past / Demon Slayer: Kimetsu no Yaiba

For a series where humans put their lives on the line to fight man-eating Demons, it's no surprise that Demon Slayer: Kimetsu no Yaiba has a ton of characters with tragic backstories, be it human and demon.

Warning: All Spoilers Unmarked

Humans

• The series' premiere/first chapter starts off happily for the Kamado family; Tanjiro Kamado is out selling charcoal for his tightly-knit family despite the loss of their father due to illness. Then when he comes back, all the Kamados are slaughtered, leaving his eldest younger sister, Nezuko as the Sole Survivor, but to add insult to the injury, she is turned into a demon. This triggers Tanjiro into embarking on a quest to cure Nezuko, while at the same time avenge his family from the demon responsible: Muzan Kibutsuji.
• Zenitsu Agatsuma, like almost everyone in the series, was an orphan. However, he was taken under the wing by the former Thunder Hashira, Jigoro Kuwajima, after him using money to appeal to a girl he fell in love put him in debt after she left him for someone else. Even then, his cowardice severely hindered his training progress, gaining the ire of his fellow trainee, Kaigaku, who repeatedly antagonized him despite Zenitsu having respect for his superiority. Zenitsu, like Tanjiro, Inosuke, Kanao, and Genya, survives the Final Selection, but it takes a lot for him to fully overcome his repeated cowardice throughout the entire series.
• Inosuke Hashibira is just one of a handful of characters whose lives were tragically altered by Doma, the Upper Rank Two Demon. Originally living with a loving mother, Kotoha, but an abusive father, both him and his mother escaped from the father's wrath and eventually found some form of solace in Doma's Paradise Faith cult. However, when Kotoha finds out about Doma's true nature, she attempts to escape alongside Inosuke, but is forced to throw him off a cliff in an attempt to save him before Doma finds and devours her.
• Kanao Tsuyuri grew up in an abusive household from both of her parents, resulting in her mind and emotions stopped from functioning to cope with her situation. She would eventually be sold off into slavery before being bought by the Kocho sisters and raised as their adopted sister. Even that isn't enough to experience further tragedy, as Kanae is murdered by Doma, all the while Kanao fails to even mentally function without being given orders or flipping a coin.
• Sakonji Urokodaki was the former Water Hashira who trained Tanjiro into becoming a Demon Slayer. However, Urokodaki has lost countless apprentices to the Hand Demon prior to crossing paths with Tanjiro, putting him into far more intense training than his past pupils, at one point placing in a seemingly unbreakable boulder as a means to prevent him from entering into the Final Selection out of safety.
• Giyu Tomioka grew up alongside his older sister, Tsutako, before the latter sacrificed herself to protect him from a Demon. When Giyu tries to tell others of his story, he was deemed a heretic and was sent to live with one of his relatives (a doctor) before running away, nearly dying in a mountain, and was rescued and apprenticed under Sakonji Urokodaki. It was there he met Sabito, his Best Friend who would eventually save him from a demon's attack before being killed by the Hand Demon, something Giyu wouldn't know until about a week later. This caused Giyu to suffer from guilt from both his sister's and his friend's deaths, as well as feeling inferior to Sabito, as Giyu believed he would've been a far more better Water Hashira than he is.
• When Shinobu Kocho was young, she and Kanae were raised in a loving and caring household, living happily with their parents. Unfortunately, their parents tragically was killed by a demon, right in front of Shinobu and Kanae, and they would've lost their lives too if it wasn't for the arrival of Gyomei, who killed the demon and rescue the Kocho sisters. Due to this, they both joined the Demon Slayer corps. Years later, she would later lose Kanae at the hands of Doma. She also lost nearly all of her Tsugukos and the families of her apprentices under her care. This caused Shinobu to have a personal hatred towards demons, to which she hides under a friendly facade, similar to Kanae.
• Kagaya Ubuyashiki was one of the many victims of a family curse in which he would suffer an illness that would slowly afflict his entire body until his death at an early age due to his relation to Muzan. And that's not even counting his father's suicide at the age of 19, being a sensitive man who could not bear the thought of his troops getting hurt or dying, in addition to the rest of his brothers also dying presumably to the curse.
• Kyojuro Rengoku has always been diligent and duty-bound, but he comes from a position where he had to become the sole emotional steadfast figure of his family after his mother died by succumbing to illness, as well as his father losing himself to alcohol as a result from that and losing faith in his swordsmanship; Kyojuro had to be strong for his brother who felt useless due not having the talent to be a swordsman and having a father who became a wreck that just yelled at his sons, while he himself had nobody else to rely on. With all that, Kyojuro doesn’t falter, really becoming a man who isn’t held back by his family issues, not once blaming his father for anything, even if the visualization of his subconscious core implies that really deep down Kyojuro had some fragility he had to hide deep within.
• Tengen Uzui's backstory is rather unique. In his father's efforts to save the Shinobi clan, he and his siblings were subjected to overzealous training, some of which involved Tengen being ordered to kill two of his brothers without even knowing who he fought. And if that's not enough, his father influenced Tengen and his surviving younger brother to believe that they needed to dispose innocent lives for their benefit, and solely have a wife as means for producing offspring. Appalled by his brother embracing the mindset, it's no wonder Tengen left the clan and eventually joined the Hashira.
• Muichiro Tokito definitely had it rough. He lived together with his older twin brother Yuichiro who was strict and tried to drill his kindness out of him due to the fact their father died trying to find herbs for their sickly mother. Then one night, a demon came and attacked Yuichiro, causing Muichiro to snap and kill the demon. By the time he returned to his brother, he was on the verge of death begging for the gods to spare his kind brother and punish him instead. He then spent a few days watching his brother's corpse and himself be eaten by maggots and would have died had Ubuyashiki's wife and children not rescued him. The trauma of the incident caused Muichiro to completely shut himself off emotionally.
• Mitsuri Kanroji's backstory leans more toward personal insecurity, as the rejections she received from potential suitors resulted in her dying her hair and looking weak just to appeal to men in hopes of marriage, even if it continued to negatively impact her well-being. It was only when she encounter Kagaya Ubuyashiki, who told her to reject normalcy and embrace who she was as her strength was a gift, that she began to accept herself and join the Hashira.
• Obanai Iguro, and a rather nasty one too. He was born into a clan of thieves who worshiped a female snake demon, who had a taste for newborn babies. Being the first boy of the clan (since majority of the clan were born female), he mostly lived in a cell for the beginning of his life placed by his family and was stalked by the snake demon, who took a liking to him due to being male and his heterochromia eyes, frightening him to the point of not getting any sleep. When he was younger, the snake demon forced his own family to have his mouth split open from ear to ear, just so he could resemble her face, due to her liking towards him. Because of this, he's been trying to find the means of escaping all while living under constant fear of both the demon and his family. When he finally does, the Snake demon killed all 50 of his relatives and began pursuing Obanai and nearly killed him, before he was saved by Shinjuro Rengoku, who managed to slain the demon. When he reunited with an older cousin of his, she violently rejected him, blaming him for the death of their family and insisted that he should've let the demon eat him. Because of this, Obanai began having PTSD of his past and became a cynical Death Seeker, hoping that he would die to atone for the sins of his family.
• Gyomei Himejima was a priest that took care of orphans in a temple, being an orphan himself. One night, one (later revealed to be Kaigaku) sacrificed the others' lives to save his own from a demon by removing the wisteria incense, causing the demon to enter and slaughter nearly everyone. Desperate to save one of them, Gyomei attacked the demon and killed him brutally. The lone orphan that witnessed the event called Gyomei a monster in her confusion, causing him to almost be executed had Ubuyashiki not intervened. Author notes reveal that the child had actually been referring to the intruder as a monster, but had been unable to articulate things clearly because she was in shock, and that Himejima's imprisonment is her biggest regret even ten years later.
• Want to know why the Shinazugawa brothers are such mean-spirited jerks? Their backstories could reveal the answer.
  • Genya, like Inosuke, also had an abusive father but a loving hard-working mother who cared for her children, including Genya's older brother Sanemi, the future Wind Hashira. With his father hated by the community and stabbed to death by an unknown assailant, Genya vowed to protect his family alongside Sanemi. However, his mother was turned into a demon and slaughters all of Genya's younger siblings before being taken down and killed by Sanemi, leading to a misunderstanding in which Genya severs ties with his brother by accusing him of murdering their mother, before realizing that his mother was the demon that Sanemi was forced to slaughter. Since then, Genya develops a mean-spirited attitude despite joining the Demon Slayer Corps against his brother's wishes in hopes of reconciling with him.
  • Back when Sanemi was young, he was the eldest brother of seven siblings, including Genya, and they live with both their parents, with their father being abusive man towards his children, as well towards his wife, until the man finally met his end by someone who had a grudge on him. Afterwards, he resolved to supporting his family, alongside his mother and Genya. However, his mother tragically became a demon and killed all of her children, excluding Sanemi and Genya. Sanemi was then forced to cut down his mother, which placed him in a state of shock, as he watched Genya screaming in tears and accusing Sanemi of being a murderer, not knowing that his own mother was responsible for killing the rest of their siblings. Years later, he would meet Masachika Kumeno, who would introduce him to the Demon Slayer corps and the two quickly became friends. Unfournately, Kumeno lost his life during their battle against a Lower Rank Moon demon, which caused Sanemi to suffer guilt on losing one of his only friends. Add on to the fact that his crush, Kanae Kocho, was murdered by Doma, and no wonder why he's so bitter and angry towards demons.
• Even though Yoriichi Tsugikuni was arguably the strongest Demon Slayer to ever walk the earth, he was still a man of tragedy. At birth, Yoriichi was almost killed by his father because of the Demon Slayer Mark on his forehead. While he was saved by his mother Akeno, he was treated as an outcast by his father and the rest of the family. He was isolated in a small room, fed poor food, given poor education and clothing, and—as the Sengoku rumors revealed—was verbally abused by his father to the point where he thought of erasing his own existence at two years old. It’s revealed that Yoriichi knew that his mother was dying from an illness and tried to support her as much as he could. Upon her death, Yoriichi ran away from home to protect his brother from the same abuse his father had inflicted on him, meeting a girl named Uta, who he eventually falls in love with and marries. However, his wife and unborn child would eventually be killed by a demon, resulting in him becoming a Demon Slayer. Yoriichi would later confront Muzan himself and almost kills him. However, Muzan flees just as Yoriichi was about to finish him off, leaving him feeling guilty that his failure meant that plenty of people would lose their lives. And that's not counting the fact that Yoriichi realizes that his beloved older brother—Michikatsu—had betrayed them and took the path of a demon, Muzan's Dragon. He then proceeds to take responsibility for failing to kill Muzan, setting Tamayo free, and Michikatsu turning into a demon, causing the demon slayers to turn on him and demand his death, resulting in his banishment from the Demon Slayer Corps shortly afterward. Talk about a rough life.

Demons

• Muzan Kibutsuji of all beings (even though it does NOT excuse his actions one bit). As a human, he was in a constant struggle of survival in account to his frailty, being deemed stillborn when entering the world (and nearly cremated before giving out his first cries), continuing to struggle with illness as he grew, and eventually contacting a disease that would kill him before reaching 20. The doctor treating Muzan gave him a special experimental medicine that appeared to have failed, with Muzan killing him in a rage of his condition worsening, before realizing that it worked and ultimately turning him into the first flesh-eating demon (not that it really mattered to him much). Realizing the side effect of not being able to safely walk in the sun, he becomes obsessed with finding the Blue Spider Lily, while also spreading his influence by creating more demons, with the hope that one of them has the power to survive in sunlight so he could consume them and ultimately gain immortality.
• Nezuko Kamado, like her brother Tanjiro, lived happily with the rest of the Kamado Family (sans her long deceased father), as shown as she happily greets her brother while he is off to sell charcoal. Of course, that all changes when Muzan attacks and murders her family, but it doesn't stop there. Despite being the sole survivor of the ambush, she is turned into a demon, and it takes restraint from Tanjiro for her to tearfully recognize him and cut her initial habit into eating humans. Tanjiro would go through all the painstaking attempts throughout the entire series in an effort to ultimately restore her humanity.
• When she was a human being, Lady Tamayo fell ill with a life-threatening disease at the age of 19 and searched for a cure. She then came across Muzan Kibutsuji, who offered her a way to treat her illness. She foolishly agreed and as a result, became a demon, which caused her to committing a murderous rampage around her hometown, killing her husband and their children, as well as a number of innocent civilians. When she found out what she did, she was horrified and fell into despair. She then became an unwilling servant to Muzan, having no hope that the Demon King could be defeated, until Yorichii frees her from Muzan's control.
• Teoni, the Hand Demon that Tanjiro faces in the final selection, used to be a meek child who always wished to have his hand be held by his older brother, but then was turned into a demon and became a man-eating monster, with his own older brother being among his first victims. After regaining his human memories, when he remembered his brother who always comforted him by holding his hand, and how he was the one who killed him, expressing remorse over his deed at his last living moments. It's no wonder why Tanjiro began to have sympathy for the demons under Muzan's control.
• Kyogai was an aspiring writer and musician as a human, but his own father, whose approval he sought, constantly mocked and belittled his abilities, which ended up getting him killed when Kyogai became a demon.. Even he couldn't catch a break as a member of the Twelve Kizuki, as he is booted off the Lower Ranks once he's reached his human-eating limit and thus, couldn't grow any stronger. So when Tanjiro finally recognizes his talents and says it out to him, Kyogai couldn't help but share happy tears as he dies.
• Some of the Spider Demons in the Natagumo Mountain Arc clearly had it rough.
  • Rui, the Lower 5 of the Twelve Kizuki, was born weak, leading to his parents asking a doctor to grant him a strong body. Since the doctor was actually Muzan, Rui ended up getting turned into the flesh-eating demon. Wanting to atone for their mistakes, his parents planned to kill him, then themselves, but Rui, feeling betrayed, kills them first. This was what led to his obsession with familial bonds despite losing his memories. It's only in his last moments that he remembers it, and that his mother's last words were an apology for not giving him a strong body.
  • Similar to her master, Rui, the Spider Mother Demon was just an ordinary little kid before she turned into a demon. When Rui met her, he forcibly altered her appearance into that of an adult woman's so that she could be the mother to fill the void for Rui himself. If that's not enough, her new "family" horrifically abuses her for the smallest mistakes. It's no wonder why Tanjiro decides to give her a "mercy kill" so that her death would meant freedom from Rui's control.
• You can't help but feel sorry for Gyutaro and Daki after everything both of them went through leading up to their demonic transformation.
  • Gyutaro was dealt a horrible hand in life, being born in extreme poverty to a sickly and mentally unstable prostitute mother who abused him for being nothing more than a burden. And that's not even considering the fact that his hideous looks attracted abuse from bystanders as well. It was only until he was able to become a skilled fighter and his sister, Ume, was born, that he found happiness, but even that didn't last too long when Ume is burned to near death after getting into a defensive altercation with a sleazy samurai. And because no one gave a damn about them, even Ume's current state, it's no wonder Gyutaro gave in to Doma's influence and became a demon alongside Ume.
  • Daki on the other hand was born beautiful, however this led to her mother being actually jealous and terrified of Ume’s natural beauty; this irrational jealousy of her own daughter prompted her to one day try to cut Ume’s hair out of spite. Even when Gyutaro became Ume's protector, an encounter with a sleazy samurai while the former was working resulted in Ume being burned alive. And unlike Gyutaro who gave in to Doma's influence in becoming a demon, Daki didn't even have a choice: she was barely conscious and too young to make that decision for herself.
• Akaza just might possibly have one of the saddest pasts to be ever seen. He was once a young fighter named Hakuji, who stole in order to get his sick father's medicine. Then his father hanged himself while wishing for his son to live a virtuous life instead of continuing to steal for him. And then he was taken in by a kind martial artist by the name of Keizo and fell in love with Keizo's daughter, Koyuki. After a few years of happiness together, Keizo and Koyuki were murdered by a rival dojo, while Hakuji was out of town. Hakuji killed all of the members of the rival dojo, in a single night, and then encountered Muzan, who turns him into a demon after being impressed with his strength and the brutal massacre he unleashed.
• It's a bit downplayed in Doma's case, as he spent his childhood being worshipped and treated as a god by a scam cult for his unnatural looks. However, it's clear that despite (or possibly leading to) his amoral lack of empathy, he was not raised in the right. His parents were con-artists that groomed Doma from a very young age to be a priest/icon of their aforementioned cult. His father used his position to sexually exploit the women of the cult, causing the mother to murder him and then commit suicide in front of Doma, who was still a small child. And because Doma was too young (and perhaps too brainwashed) to even understand tragedy, he simply brushed off their deaths as a property stain.
• The tragedy in Kokushibo's human life as Yoriichi's older twin brother, Michikatsu, comes from a succession of choices he made and had no one else to blame but himself, unlike several of his fellow Kizuki members who suffered under completely external factors. Michikatsu chose to harbor jealousy over Yoriichi's talent which nurtured a massive inferiority complex, to the point he created his own false memories of absolutely hating Yoriichi over the centuries in order to force himself to believe his choices were valid, not petty. If that's not enough, Michikatsu chose to abandon the life as the head of the Tsugikuni family, leaving his wife and children behind to pursue strength under Yoriichi's teachings, while trying to become a Demon Slayer himself to keep up with Yoriichi. Eventually, Michikatsu chose to betray the Demon Slayer Corps with the growing fear of dying under the effects of the Mark and wasting all the years he gave into perfecting his martial arts, turning into the demon Kokushibo to retain all of it. As Kokushibo is about to die, he is left with nothing but regrets, coming to terms all of his efforts to remain alive as a demon led to absolutely nothing truly beneficial to him, and he just couldn't hate Yoriichi as much as he believed he did, wondering why he was even born.

---