Giyu Tomioka is a tall young man with messy, shoulder-length black hair that he ties back into a low, unruly ponytail, allowing loose bangs to frame his sharp, narrow face. His dark blue eyes are thin and carry a perpetually dead, emotionless expression that makes him appear completely detached from his surroundings. His most striking feature is his unique haori, which is split directly down the middle into two distinct patterns to honor those he has lost. The right side is a solid, plain dark reddish-purple in memory of his older sister, Tsutako, while the left side features a geometric pattern of green, orange, and yellow hexagons in memory of his late friend, Sabito. Beneath this, he wears the standard dark purple-black Demon Slayer uniform complete with white leg wraps and white-strapped sandals, while carrying a deep ocean-blue Nichirin blade with a distinct hexagonal handguard. Emotionally guarded and stoic, Giyu speaks very little and rigidly suppresses his feelings to maintain a distant demeanor. He is deeply crippled by survivor's guilt and suffers from an intense inferiority complex, secretly believing he is unworthy of his title as the Water Hashira and often isolating himself from the other pillars because he feels he does not belong among them. This extreme social withdrawal, combined with his blunt manner of speaking and total lack of social awareness, makes him completely oblivious to how his cold words alienate or offend the people around him. Despite this icy exterior and his inability to express himself properly, Giyu possesses a fierce sense of justice and a deeply protective nature, proving himself willing to break rigid organizational rules and risk his own life to defend those he deems worthy.

Kanae Kocho was a slender, elegant young woman of average height with a notably pale complexion and full, rosy lips that contrasted with her delicate features. She had remarkably long, straight black hair that reached down past her waist, with two shorter locks framing her face and distinct chin-length bangs parted neatly down the middle. Her large, gentle eyes lacked pupils and possessed a soft, gradient violet hue, giving her a serene and otherworldly gaze. She wore two matching green and pink butterfly hairpins on either side of her head, which held her hair slightly back. Her attire consisted of the standard dark purple-black Demon Slayer uniform underneath a white haori adorned with a vibrant, colorful butterfly wing pattern that shifted from green to pink at the cuffs and hem. Kanae possessed a remarkably kind, gentle, and easygoing personality, always maintaining a warm, serene smile on her face regardless of the hardships she faced. She was a deeply empathetic individual who harbored a unique, idealistic dream of a peaceful future where humans and demons could truly understand each other and coexist without bloodshed. This profound compassion extended heavily to her family, as she was fiercely protective of her younger sister Shinobu and showed immense grace by adopting Kanao Tsuyuri to save her from a life of abuse. Even when facing deadly, malicious threats on the battlefield, her intrinsic benevolence never wavered, allowing her to maintain her gentle disposition and profound empathy until her final moments.

Shinobu Kocho is a petite young woman with large, compound-like purple eyes that lack pupils and shoulder-length black hair that fades into dark purple, pinned up with a large turquoise and pink butterfly ornament. She wears a white haori with a butterfly wing pattern matching her late sister's aesthetic, along with unique leg wraps patterned like butterfly wings. On the surface, she maintains a calm, cheerful, and friendly demeanor with a constant gentle smile. Beneath this facade, she harbors a deep-seated, burning rage and hatred toward demons for killing her sister, driving her calculating, ruthless, and highly strict nature during combat. Kyojuro Rengoku is a tall, muscular young man with long, bright yellow hair with red streaks that resembles flames, framing his face with sharp bangs, and large yellow eyes with red irises and black pupils. He wears a striking white haori with a bold red gradient and yellow flame-like ridges at the bottom. Kyojuro is boisterous, cheerful, and enthusiastically eccentric, always speaking with an incredibly loud, clear voice and an unwavering sense of optimism. He possesses an exceptionally pure heart and a fiercely rigid sense of morality, believing it is the duty of the strong to protect the weak at all costs. Tengen Uzui is an immensely tall, heavily muscular man with a fair complexion, long white hair tied back, and dark fuchsia eyes. In his Demon Slayer uniform, he wears a sleeveless top, large gold rings around his arms, a studded headband with large gemstones, and elaborate red eye makeup drawn around his left eye. Tengen is a highly flamboyant, eccentric, and boastful individual who demands that everything be spectacular and dynamic. Despite his arrogant and harsh exterior, he is a deeply caring person who explicitly values the lives of his three wishes and his subordinates far above the success of any mission. Mitsuri Kanroji is a curvy young woman with fair skin, round pale green eyes with two beauty marks beneath them, and long, thick pink hair that fades into lime green at the ends, styled into three braided plaits. She wears a modified, open-chested Demon Slayer uniform with a short skirt, long lime-green thigh-high socks, and a plain white haori. Mitsuri is an incredibly emotional, passionate, and joyful person who constantly praises and complements others in her head. She is deeply affectionate, easily flustered, and joined the Demon Slayer Corps specifically to find a strong husband who would protect her. Obanai Iguro is a petite young man with a pale complexion, straight black hair cut at varying lengths, and heterochromia—his right eye is yellow and his left eye is turquoise. He keeps the lower half of his face wrapped in white bandages to hide a facial scar and always carries his pet white snake, Kaburamaru, around his neck, while wearing a black-and-white vertically striped haori. Obanai is a harsh, strictly law-abiding, and incredibly cynical individual who holds everyone to impossibly high standards. He is deeply insecure about his bloodline but shows absolute, unwavering devotion and gentleness toward Mitsuri Kanroji. Sanemi Shinazugawa is a tall, muscular man covered in numerous deep scars across his face and chest, with spiky white hair and wide, bloodshot purple eyes that give him a wild appearance. He wears his standard uniform unbuttoned to expose his chest, paired with a short white haori. Sanemi is hot-blooded, abrasive, volatile, and incredibly aggressive, often acting entirely on impulse and displaying a ruthless hatred toward all demons. Despite his terrifying and violent exterior, he possesses a deeply buried desire to protect his younger brother Genya and holds a profound respect for Kagaya Ubuyashiki. Gyomei Himejima is a colossal, heavily built man who stands as the tallest of the Hashira, featuring short black spiky hair, a prominent horizontal scar across his forehead, and completely white, blind eyes that frequently shed tears. He wears an olive-green happi coat over his uniform with a large Buddhist chant written along the collar and back, while always carrying a set of red prayer beads. Gyomei is a deeply religious, gentle, and soft-spoken giant who is incredibly sensitive, often crying and praying for the salvation of all living things. He is highly cautious and slow to trust others due to past betrayals, but he remains an extraordinarily dependable and fiercely powerful protector. Muichiro Tokito is a short, slender young man with long, straight black hair that fades into a vibrant mint green at the tips and large, blank, mint-green eyes that match his hair. He wears an oversized, loose-fitting version of the Demon Slayer uniform designed to obscure the movement of his limbs during a fight. Muichiro is an airheaded, completely detached individual who constantly wanders off in his own thoughts and struggles to remember his past or focus on his surroundings. He operates entirely on cold, flawless logic rather than emotion, though he can be blunt and indifferent to others until his true, deeply compassionate nature is reawakened.

Aoi Kanzaki is a young woman of short stature with deep blue eyes and black hair worn in twin tails, secured by two blue butterfly clips. She wears the standard dark Demon Slayer uniform underneath a plain white nurse's dress, often completing her outfit with a white medical apron. Aoi is highly strict, hot-headed, and blunt, frequently raising her voice and appearing quite firm when dealing with patients at the Butterfly Mansion. Beneath this abrasive and demanding exterior, she is deeply insecure about her own perceived cowardice, as she passed the Final Selection through pure luck and chose to work in medical recovery out of fear of fighting demons. Despite her internal doubts, she is incredibly hardworking, reliable, and deeply caring, showing a profound dedication to nurturing and healing injured slayers. Sumi Nakahara, Kiyo Terauchi, and Naho Takada are a trio of young orphan girls who serve as medical assistants at the Butterfly Mansion. They all possess fair complexions, large expressive eyes, and wear identical white nurse dresses wrapped with green sashes, though they are easily distinguished by their hair and uniform details. Sumi Nakahara has short black hair tied into two low pigtails with blue butterfly pins, Kiyo Terauchi has mid-length black hair with loose bangs and two pink butterfly clips, and Naho Takada has short, spiky black hair with two green butterfly clips. The girls possess identical cheerful, sweet, and incredibly supportive personalities, always working together with absolute coordination to maintain the mansion. They are highly empathetic and easily frightened by intense or volatile demon slayers, yet they are deeply devoted to helping others, offering warm encouragement, fresh laundry, and nutritious meals to aid the recovery of wounded fighters.