Kisa Sohma is one of the younger members of the Sohma family, cursed by the spirit of the tiger of the Chinese zodiac. When her body undergoes physical stress or when she is embraced by a person of the opposite sex, she transforms into a small, golden tiger cub. As a result of her curse, Kisa possesses distinctive physical features, including naturally golden hair and large amber eyes, which are often considered unusual in a Japanese school setting. She is depicted with a petite frame and a slender build, often dressed in feminine clothes and occasionally styling her hair with ribbons.

At her introduction, Kisa is characterized by a deep sense of shyness and withdrawal, having stopped speaking entirely. This silence stems from severe bullying she faced when she started middle school. Her classmates first mocked her unusual golden hair and eyes, and when she ignored their taunts, they escalated to ignoring her completely, only breaking their silence to laugh at anything she tried to say. Ashamed of the situation and unable to explain why she was being targeted, Kisa did not confide in her worried mother. Fearing that her mother would be disappointed in her for being weak, Kisa ran away from home. It was during this time that she was found and brought to Shigure Sohma's house by Hatsuharu, who shares a close brotherly bond with her.

A significant part of Kisa’s development is facilitated by Tohru Honda. Having experienced bullying in her own past, Tohru understands Kisa's pain and helps her confront her fears. Through Tohru's unwavering kindness and acceptance, Kisa begins to heal, finding her voice again and learning that she is loved for who she is. She grows extremely attached to Tohru, affectionately calling her onee-chan, which translates to big sister. Tohru serves as a pivotal figure, and Kisa becomes fiercely protective of her, often getting frustrated with her best friend, Hiro Sohma, when he is rude to Tohru.

Her relationship with Hiro, the zodiac spirit of the sheep, is central to her story. They are best friends, and although Hiro cares for Kisa deeply, he once told Akito, the head of the family, that he loved her. In retaliation, Akito beat Kisa severely, an injury that took weeks to heal. In an attempt to protect her from further harm, Hiro distanced himself from Kisa just as her school troubles began, which added to her feelings of isolation. Despite his often brusque demeanor, Kisa trusts him and values his guidance, though she is sometimes oblivious to his jealous or romantic feelings. Over the course of the series, their friendship mends and deepens, with the implication that they eventually form a romantic couple.

Kisa also shares meaningful connections with other cursed members. She looks up to Hatsuharu as an older brother, and he is one of the first people to search for her when she runs away. She relates to Yuki Sohma, who also endured bullying and a period of muteness in his childhood, and he encourages her to grow stronger alongside him. Although initially intimidated by Kyo Sohma, she considers him another older brother figure, and overcoming her shyness enough to greet him directly is considered a major personal accomplishment.

Kisa’s primary motivation throughout the narrative is to overcome her paralyzing shyness and fear of rejection. She strives to be brave, to speak for herself, and to face her problems instead of running away from them. Her journey is one of healing, as she learns to accept the physical traits born from her curse and to embrace her own self-worth. In the final chapters of the story, Kisa experiences the breaking of her zodiac curse, a change she feels subconsciously as a bittersweet release. Her notable abilities, beyond the involuntary transformation into a tiger cub, are largely emotional and social; she demonstrates a remarkable capacity for loyalty, kindness, and a quiet determination to become stronger for the sake of those she loves.