Hitomi Sata, mother to Reika and Kyouya Sata, resides separately from her husband in Kobe under circumstances equating to divorce. This separation during her children's formative years deeply affected Kyouya, causing him to withdraw emotionally from family bonds. Hitomi persistently shoulders blame for Kyouya's distrust of love, convinced he resents her maternal absence, though she later recognizes his enduring affection despite their fractured past.

Her personality radiates warmth and kindness, contrasting her children's complex natures. She lacks their concealed harsh edges, projecting unwavering gentleness. Alcohol unveils a childlike facet of her character, marked by peculiar jokes and fervent attempts to spread cheer—behavior rooted in guilt over past familial strife.

Physically, Hitomi mirrors Kyouya strikingly, sharing his distinctive blonde hair color and texture, a visual testament to their kinship. Her name, 瞳 ("pupil of the eye"), aligns with her role as an observer of her family's emotional currents.

Hitomi shares a home with Reika in Kobe, while Kyouya lives with his father in Tokyo. This distance strains their relationship, though Kyouya's girlfriend Erika Shinohara occasionally facilitates visits to bridge the gap. The narrative centers on her maternal impact and the divorce's repercussions, particularly Kyouya's emotional turmoil, without elaboration on her profession or origins.