Shinobu was a petite, young woman of slender build. Her complexion was notably pale, contrasting with her pink lipstick. She had large, pupil-less eyes that resembled those of insects. Her irises featured a hazy purple gradient that darkened toward the bottom, accented by white highlights at the top. Her eyes were framed with black eyelashes. She had hair that was raven-black, fading into a dark purple hue at the ends. Her hair was styled at the back of her head into a flat yakai-maki bun, fastened with a white butterfly ornament that consisted of a light purple trim on the outer side of the wings along with turquoise speckled spots. She had center-split, ear-length, voluminous curtain bangs that flowed down to frame the sides of her face, with two thinner chin-length locks of hair in front of her ears below. By the time of Hashira Training, both her bangs and locks were visibly more refined and longer. She stood out among the more physically imposing Hashira due to her diminutive stature and small frame, which was later reinforced by her mentioning that she did not possess enough physical strength to decapitate a demon as the others do. Shinobu wore a dark purple-tinted variation of the standard Demon Slayer uniform. It consisted of a button-up jacket with a stand-up collar and long sleeves. The uniform also featured 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 were also tinted dark purple and were fastened at the waist with a white belt. Her legs were wrapped with a pair of unique white kyahan—with butterfly-patterned design—that transitioned from pale turquoise to pink gradient around the lower legs, tied securely with white ribbons. Her tabi socks matched the dark purple color of her uniform. Over her uniform, she wore a distinctive haori that once belonged to her late older sister, Kanae. The haori matches the pattern on her kyahan, decorated with a butterfly wing pattern inspired by the Monarch Butterfly. Like the kyahan, it featured a color gradient that shifted from white to pale turquoise and to pink. The cuffs and hem had a black trim decorated with pale turquoise dots. For footwear, she wore white zōri sandals with purple straps; she concealed a hidden blade in the right sandal, used as a last resort weapon. Shinobu displayed a friendly and cheerful demeanor, always having an easygoing smile on her face regardless of the situation she was in. However, her outward behavior was shown very quickly to be a façade. Despite her relaxed exterior and her initial claim of wanting to get along with demons, she could be cruel towards them. Underneath the mask, she held an intense hatred for demons due to the loss of her beloved older sister, Kanae, along with the deaths of her parents, almost all of her Tsuguko (successors), and the families of her apprentices at the Butterfly Mansion. This hatred was so strong that she was in a near-constant state of extreme anger. 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'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. Eventually, she developed her gentle, positive attitude, and mannerisms to match, while internally holding in her rage. She clarified that this behavior was fueled by her desire to continuously display the smile that her sister had loved. Although she feigned an optimistic demeanor to hide her vexations, Shinobu was genuinely compassionate to her fellow humans. After Kanae's death, Shinobu coddled all the orphaned girls in her care as if they were her own sisters. In addition, despite being initially irritated by Kanao's passivity, Shinobu grew to have a more stable relationship with her adopted sister. She comforted Kanao during Kanae's funeral despite Kanao not shedding tears, being perfectly understanding of her reasoning for not expressing emotions, and expressed concern for Kanao's well-being when she warned Kanao about the grevious effects of Flower Breathing's Final Form'.