Shinobu Kocho.

Shinobu is a petite, young woman with a slender build and a fairly pale complexion. She has large eyes that lack pupils, only a haze of gradient purple that blends with violet and dark purple with white highlights on the upper irises, making her eyes appear similar to those of insects, and rose pink lips. She had a raven-black wavy hair that fades into a dark purple hue at the ends, styled at the back of her head into a flat yakai-maki bun fastened with a white butterfly ornament with a light purple rimmed, along with turquoise speckled spots. She had a center-split, ear-length, voluminous curtain bangs that flow down to frame the sides of her face, with two slightly thinner chin-length locks of hair in front of her ears below them. She stands out among the more physically imposing Hashira due to her diminutive stature and small frame, which is later reinforced by her mentioning that she does not possess enough physical strength to decapitate a demon as the others do. According to Zenitsu Agatsuma, Shinobu is so cute that she could make a living on her looks alone.

Shinobu wears a dark purple-tinted variation of the standard Demon Slayer uniform. It consists of a button-up jacket with a stand-up collar and long sleeves, featuring gold buttons and a shirt pocket on the left breast, with the kanji for Destroy (滅めつ, Metsu?) engraved on the back of the uniform. Beneath the jacket, she wore a white long-sleeved collared undershirt. Her long, saggy tattsuke-hakama pants are also tinted dark purple and are fastened at the waist with a white belt. Her legs were wrapped with a pair of unique white kyahan—with butterfly-patterned design—that fades from pale turquoise to pink gradient around the lower legs, and tied securely with white ribbons. Her tabi socks match the dark purple color of her uniform. Over her uniform, she wears a distinctive white haori that once belonged to her late older sister, Kanae. The haori features a butterfly wing pattern inspired by the Monarch Butterfly, with a color gradient that fades from white into pale turquoise and then pink on the sleeves and hem, that are cuffed with a black trim, with pale turquoise dots, resembling butterfly wing edges. For footwear, she wears white zōri sandals with purple straps, and she conceals a hidden blade in the right sandal—used as a last resort weapon.

Shinobu displays a bright, friendly and cheerful demeanor, always having an easygoing smile on her face regardless of the situation she is in. However, her outward behavior is shown very quickly to be a façade. This is displayed in the way she enjoys teasing others, to the point of being rather sardonic about it, enjoying most notably to pick on Giyu Tomioka. Despite her relaxed exterior and her initial claim of wanting to get along with demons, she can be rather cruel towards them, which is seen when she kills the Spider Daughter after giving her false hope of helping her, and immediately attempting to kill Nezuko Kamado without giving her brother Tanjiro a chance to prove that she was harmless to humans. Later on, she is shown to have a more compassionate side towards the Kamado siblings after hearing their full story. She also showed to be very strict when she needed to, as she scolding Inosuke when he breaks the window. It is later revealed that Shinobu's outwardly calm and tranquil disposition is worn as a mask, as she holds an intense hatred for demons due to the loss of her beloved sister Kanae at a young age, along with the deaths of her parents, almost all of her Tsuguko, and the families of her apprentices at the Butterfly Mansion. This hatred is so strong that she is in a near-constant state of extreme anger, which is sensed by Tanjiro when the two held a conversation. Her desire for revenge rendered her unable to live the normal life her elder sister had wished upon her, instead devoting the entirety of her energy to defeating demons. Shinobu also reveals that she suffers from an inferiority complex due to her inferior physical abilities compared to her fellow Hashira, having been jealous of them for possessing taller or more muscular bodies than her and cursing her own body for not developing further to make her more effective in combat.

Shinobu's younger self had a more brash, blunt and uncomplicated demeanor as seen when she rescued Kanao Tsuyuri, whom she had a negative attitude towards raising at first. After the death of Kanae, however, Shinobu began to outwardly behave more like her older sister and eventually developed her gentle, positive attitude and mannerisms to match while internally holding in her rage, which she later clarifies is fueled by her desire to continuously display the smile that her sister loved. Though never shown onscreen, she has a notable temper, namely in the way that makes even the loud and brash Inosuke Hashibira take notice.

As a Hashira of the Demon Slayer Corps, Shinobu was a very powerful and skilled combatant. Despite not possessing the physical strength to cut off a demon's head common to that of an average Demon Slayer, she uses her creativity, ingenuity and techniques to more than make up for it. Instead of the traditional method of decapitating a demon with a Nichirin Sword to kill them, she opted to use a modified version of a katana that acts as a stinger to inject a powerful wisteria-based poison that is lethal to demons. In addition to her intellect, she is extremely fast and agile, allowing her to overpower demons very quickly. She possesses tremendous speed and reflexes enabling her to easily evade and out-pace demons, attacking them before they can even register what happened. Shinobu was so fast that it often appears as if she teleported

Insect Breathing (蟲むしの呼こ吸きゅう, Mushi no kokyū?): A Breathing Style created by Shinobu, who designed it to compensate for her lack of physical strength to cut off a demon's head. She has become extremely proficient in this swordsmanship style, allowing her to defeat countless demons.