10 Most Meaningful Demon Backstories, Ranked

‘Demon Slayer: Kimetsu no Yaiba’ fills its world with demons whose origins are grounded in tough human histories, broken families, and choices made under extreme pressure. These stories explain how certain powers and personalities formed long before battles ever began. Learning what each character endured makes their actions clearer and the stakes feel heavier. Here are the demon backstories that carry the most weight in the series.

Kyogai

Kyogai once worked as a talented tsuzumi drummer who was dismissed and mocked when his playing lost its edge. The humiliation pushed him toward isolation, where he fixated on regaining recognition at any cost. Muzan noticed his hunger for validation and turned him into a demon, and he later manipulated a mansion so he could finally control the rhythm around him. His demotion from the Twelve Kizuki added another wound, tying his violence directly to a need to be acknowledged.

Kaigaku

Kaigaku grew up as an orphan who survived by stealing before finding refuge at a temple. He trained as a demon slayer but resented anyone he viewed as weaker, including Zenitsu, and aimed for power without restraint. When cornered by Upper Rank One, he saved himself by accepting demon blood rather than dying as a human. His conversion explains his partial mastery of Thunder Breathing and his deep hostility toward former allies.

Tamayo

Tamayo was a sick human who accepted Muzan’s blood to live, only to realize the curse that came with it. She eventually regained enough control to separate from him and devoted herself to medical research to undermine his influence. Her work on blood chemistry and poisons turned personal tragedy into a long plan to weaken the progenitor of demons. By treating victims and studying Demon Slayer marks, she linked medicine to resistance in a way few others could.

Hantengu

Hantengu’s human life was marked by crimes he refused to own, and he constantly insisted he was innocent despite clear evidence. After becoming a demon, his body split into distinct forms that embodied powerful emotions like anger, fear, and joy. That fragmentation mirrored his refusal to accept responsibility, with each aspect shifting blame to the others. His backstory clarifies why he runs, hides, and lashes out while insisting he has done nothing wrong.

Muzan Kibutsuji

Muzan began life with a fatal condition and pursued a rare treatment using the Blue Spider Lily when he was close to death. He killed the doctor who treated him before understanding the medicine’s full effect, then later realized that treatment unlocked his demonic transformation and strength. His search for the missing flower continued for centuries as he tried to stabilize daylight resistance in himself or others. The fear of death that defined his human life remained the engine for his experiments and the creation of more demons.

Doma

Doma was born with striking features that drew followers to a new religious group when he was just a child. He lacked the ability to feel emotions and treated devotion as a puzzle rather than a bond, which led him to accept Muzan’s offer with calm detachment. As a demon, he rationalized consuming his followers as part of a larger order he believed he represented. His backstory explains his conversational politeness during cruelty and his cool fascination with human behavior.

Rui

Rui was a frail child who could barely walk, and Muzan turned him in an attempt to grant him a sturdier body. He later killed people, and when his parents tried to end his life to stop further harm, he murdered them first and only then understood their intent. That tragedy pushed him to fabricate a “family” bound by strict rules to mimic the love he had lost. His backstory shows why he forced other demons into roles like Mother and Sister and punished anyone who broke his web of control.

Daki and Gyutaro

Gyutaro grew up in poverty in the Entertainment District and protected his younger sister Ume, later called Daki, through hunger and abuse. After Daki was attacked and left to die, Gyutaro’s retaliation left them both fatally wounded until Doma offered demonhood to keep them alive. Their shared survival created a power set that depended on fighting in tandem and switching control under stress. The siblings’ early hardships explain their fierce bond and the way their abilities interlock in combat.

Kokushibo

Born as Michikatsu Tsugikuni, he trained alongside his younger twin Yoriichi, whose natural gift for swordsmanship and the Sun Breathing style far surpassed his own. Facing the limits of human aging and illness, he accepted Muzan’s blood to preserve his technique and extend his life indefinitely. He refined the Moon Breathing style and served among the highest ranks while carrying the memory of his brother’s brilliance. His backstory ties ambition and longevity to a choice that severed him from his original path as a warrior.

Akaza

Akaza lived as Hakuji, a boy who stole to buy medicine for his sick father, only to lose him and later find purpose under a martial arts master. He trained relentlessly and became engaged to the master’s daughter, but a rival dojo poisoned them, leaving him the sole survivor. In a rage, he destroyed the rival school with his bare hands, a feat that caught Muzan’s attention and led to his transformation. Everything about his techniques and his obsession with strength traces back to the people he could not save and the oath he could not keep.

Share your picks for the most meaningful demon backstories in the comments and tell us which ones hit hardest for you.