Tomoe raised her nephew Minoru Kusunoki from infancy, presenting herself as his biological mother. This deception anchored their relationship, with Tomoe embracing full maternal responsibility.

Her defining trait is extreme overprotectiveness, specifically shielding Minoru from interactions with the opposite sex. This stems from a desire to control his environment and block external influences, resulting in Minoru's social isolation and lack of typical adolescent experiences.

The discovery of Minoru's sexual relationship with Akane—Tomoe's twin sister and Minoru's actual biological mother—precipitates a profound emotional crisis. Tomoe reacts with intense fury upon recognizing Akane's resemblance to herself and the implications of their familial ties. This revelation fractures the established dynamic between Tomoe and Minoru.

Following the exposure of the truth, Tomoe transitions from anger toward reluctant acceptance. She eventually accommodates the reality of Minoru's connection with Akane. This leads to an unconventional family arrangement where both twins coexist as maternal figures to Minoru, establishing a unique household dynamic centered around him.

The relationship between Tomoe and Akane remains complex, defined by their shared history, their biological ties to Minoru, and the enduring consequences of the initial deception regarding his parentage. Their interactions reflect the ongoing adjustments necessary to sustain the reconfigured family structure.