Yuki Sohma bears the curse of the Rat spirit within the Chinese Zodiac, despite being born in the year of the Dog. He is Ayame Sohma's younger brother by ten years. His parents, fixated on family status and wealth, exploited him as a tool, favoring him over Ayame due to the Rat's elevated position. Severe childhood respiratory illness plagued him before his parents sold him to Akito Sohma, the family head embodying the Zodiac's "God." Akito inflicted prolonged psychological and emotional abuse, isolating Yuki for days in a dark room and relentlessly convincing him of his inherent worthlessness, insisting even his family and fellow zodiac members like Kyo Sohma and Hatsuharu Sohma despised him. This abuse forged deep self-esteem wounds, profound isolation, and a terror of rejection.

At annual Sohma banquets, Yuki remained isolated beside Akito until encountering Kyo Sohma, the Cat spirit. Drawn to Kyo's appearance, Yuki sought friendship, only for Kyo to react with hostility upon learning Yuki was the Rat, igniting a bitter rivalry. This rejection compounded Yuki's trauma, especially when his mother slapped him after he returned crying instead of offering comfort.

Yuki's outward princely image starkly contrasts his inner turmoil. He is an attractive, slim teenager with light grey eyes and dark grey hair, often described as androgynous – a trait causing him self-consciousness. Initially reserved, he wore Chinese-style clothing but later adopted looser, casual attire. At Kaibara High School, classmates idolize him as "Prince Yuki" for his academic excellence, calm demeanor, and kindness, spawning a fan club. Yet this admiration deepens his isolation, as he believes no one accepts his true self. He masks his insecurities with a polite, charming facade but struggles with domestic tasks and envies others' social ease.

His life shifts when Tohru Honda discovers his curse and moves into Shigure Sohma's home. Yuki develops complex feelings for Tohru, initially interpreting them as romantic, even kissing her forehead. He later realizes he sought a mother figure in her, craving the unconditional acceptance and emotional support she provided. This relationship helps him confront his past, gradually lowering his emotional barriers. He credits Tohru with giving him the courage to face his weaknesses, leading him to join the student council despite his insecurities.

As student council president, Yuki forms pivotal bonds. He befriends Kakeru Manabe, whose bluntness encourages Yuki to express his true, more sarcastic and assertive self. He also falls in love with Machi Kuragi, the council treasurer, recognizing their shared trauma from abusive childhoods. He supports Machi by subtly disrupting order around her, understanding her need to reject perfection. Their relationship becomes central to his growth, as he values being uniquely needed by her. When his curse breaks, his first act is embracing Machi.

Yuki reconciles with his brother Ayame, aided by Tohru's influence. He evolves from a reserved, self-doubting individual to someone openly expressing emotions, acknowledging his selfish tendencies, and actively supporting others. He chooses to forgive Akito and move forward rather than remain shackled by hatred. By the series' end, he describes his transformation from a "weak person" into a strong, independent human.

In *Fruits Basket Another*, Yuki marries Machi and fathers Mutsuki Sohma. He works as a teacher, maintaining his compassionate nature. His relationship with Mutsuki is supportive yet complex, reflecting his ongoing growth as he navigates parenthood and family life, including interactions with his niece Hibika and nephew Chizuru.