Tōru Honda is an orphaned high school student. Her mother, Kyōko Honda, died in a car accident shortly after Tōru entered high school. Following this loss, Tōru initially lived in a tent on the Sohma family property, choosing independence to spare her friends or grandfather burden. She supported herself through a part-time janitorial job to cover school expenses. Her father, Katsuya Honda, died of pneumonia when she was three years old. His death caused family conflict, as his relatives accused Kyōko of infidelity, claiming Tōru did not resemble him. This early loss triggered Tōru to incorrectly adopt Katsuya's overly polite speech patterns in an attempt to replace him in her mother's affections and manage abandonment fears. After Kyōko's death, Tōru kept a photograph of her mother and vowed Kyōko would remain the most important person in her life. This vow resulted in guilt whenever she perceived herself as "unfaithful," such as during academic struggles or when developing romantic feelings for Kyo Sohma.

Tōru exhibits profound empathy, optimism, and selflessness, frequently prioritizing others' needs. Her nurturing demeanor attracts the Sohma family members, with several viewing her as a maternal figure due to her unconditional acceptance. However, this outward cheerfulness masks deep-seated insecurities: she fears abandonment, struggles with low self-worth, and habitually suppresses her own loneliness and anxiety to maintain a supportive facade. Her difficulty processing grief manifests as an attachment to her mother's memory; she avoids past-tense references to Kyōko and fixates on preserving their bond. Despite her kindness, she displays occasional stubbornness and naivete, and her "airheaded" tendencies make her susceptible to manipulation by more assertive individuals.

After moving into Shigure Sohma's home, Tōru discovers thirteen Sohma family members are cursed to transform into animals of the Chinese zodiac when stressed or embraced by the opposite sex. She resolves to break their curse, motivated first by compassion but later driven primarily by her desire to free Kyo Sohma, whom she loves. This goal forces her to confront her own trauma: she gradually becomes more assertive, challenging Akito Sohma (the family's "god") and refusing to abandon her mission despite threats. Her love for Kyo intensifies her guilt over "replacing" her mother, culminating in crisis when Kyo reveals he witnessed Kyōko's accident and could have saved her had he not feared exposing his curse. Tōru rejects Kyōko's perceived final words of condemnation toward Kyo, choosing her own happiness over unresolved guilt. This acceptance allows her to reconcile her devotion to her mother with her future, understanding Kyōko would have wanted her to move forward.

In later life, Tōru marries Kyo and has three children: Hajime Sohma (a central character in Fruits Basket Another) and two unnamed younger children. She retains her core kindness and wisdom but evolves into a more self-assured individual, balancing her nurturing nature with emotional honesty. The Fruits Basket: Prelude film explores her parents' backstory, revealing how Kyo's childhood connection to Kyōko informed his guilt and later relationship with Tōru, further contextualizing her journey.