Shinobu

Shinobu was the youngest child in the Kocho family and lived happily with her mother, father, and older sister, Kanae, until her parents were killed by a demon in front of her and her sister. As the demon prepared to attack the sisters, the pillar Himejima Gyomei appeared and severed the monster's head.
After their ordeal, Shinobu and Kanae decided to become demon hunters, protect each other, and prevent others from losing what the sisters had lost.

One day, they encountered Kanao, a slave girl. Kanae decided to take her to the Butterfly Estate, though Shinobu was skeptical. Ultimately, they bought the girl and made her their follower.

Some time later, Kanae was attacked by Upper Moon 2, Douma, but managed to speak with her sister before she died. She begged her to abandon the path of demon hunters, but realized Shinobu was adamant and told her what the killer looked like.

The younger Shinobu had a more brash, rude, and outspoken demeanor, as seen when she and her sister rescued Kanao Tsuyuri, whom she held a negative attitude toward. However, after Kanae's death, Shinobu began to outwardly act more like her sister and eventually developed a positive attitude and demeanor to match her, while internally containing her anger, which she later discovers is fueled by her desire to constantly display the smile her sister loved so much. Though never shown onscreen, Shinobu has a noticeable personality, one that even Inosuke takes notice.

Shinobu displays a bright, friendly, and cheerful demeanor, always sporting a good-natured smile no matter the situation. However, her outward demeanor is a mask. This manifests itself in her love of teasing others. She told Tomioka that everyone hates him, but he denied it, saying that's not true. Despite her calm demeanor and her initial desire to get along with demons, she can be quite cruel towards them, as demonstrated when she kills the Spider Demon's daughter after giving her false hope of helping her and attempted to kill Nezuko Kamado without hesitation.
Later, after hearing their full story, she shows greater compassion for both Tanjiro Kamado and his sister. It is later revealed that her seemingly calm and serene nature is merely a mask, as Shinobu harbors a profound hatred for Demons due to the loss of her sister, Kanae Kocho, at a young age, as well as the deaths of her parents, nearly all of her Tsuguko families, and her students at the Butterfly Mansion. This hatred is so strong that she is in a near-constant state of extreme anger, which Tanjiro Kamado can sense whenever the two converse. Her thirst for revenge has robbed her of the normal life her sister desired, and she has instead dedicated all her energy to defeating Demons. During her battle against Doma, Shinobu reveals that she also suffers from an inferiority complex due to her lower physical abilities compared to her fellow Pillars, envying them for possessing taller or more muscular bodies than her, and cursing herself for not developing further to make her more effective in combat.

Shinobu is also a good teacher, as Tanjiro Kamado has noted on numerous occasions. Besides the girls at the Butterfly Estate, the girl had many other students.

Shinobu was a petite girl with pale skin and large compound eyes that had no pupils, only a gradient haze, the purple irises becoming darker the lower they went, giving her eyes an insect-like appearance. She had shoulder-length hair that faded from black to dark purple, usually tied at the back of her head in a yakai-maki style, with a white and purple butterfly-shaped hair clip. Shinobu was small in stature and was described as having a small and weak appearance, which was later backed up by her statements that she did not possess the physical strength to cut off a Demon's head like the other Hashira do.

Shinobu wore the standard Demon Slayer uniform, consisting of a dark purple black jacket with a straight lining and hakama pants that were tucked into the butterfly-patterned fabric around her legs. She also wore a white haori that belonged to her older sister, with a pattern of butterfly wings that faded to turquoise and then pink on the sleeves, with black and white dots on the cuffs, and white sandals with purple straps.