Sumire Sakura, born Sumire Kobayashi, shone as a celebrated "Mo-Ga" or "Modern Girl" in her youth, famed for her remarkable beauty. She encountered her future husband, Hiroshi Sakura, through a mutual friend. Despite initial friction during courtship stemming from Hiroshi's quiet nature, their bond deepened into marriage, integrating her into the Sakura household as daughter-in-law to Tomozo and Kotake.

Sumire diligently manages the household's wellbeing and order, overseeing finances and shopping. She frequently disciplines her younger daughter Maruko, whose misadventures and academic challenges often ignite Sumire's temper, resulting in regular scolding and occasional corporal punishment. Beneath this strictness lies genuine care; she occasionally indulges Maruko's wishes following kind acts or achievements. Sumire openly prefers her older daughter Sakiko, valuing her academic diligence and responsibility.

She shares a close, respectful bond with her mother-in-law Kotake, frequently shopping and spending time together. Sumire deeply respects Kotake's wisdom, especially concerning health and tradition. Interactions with other family members, including Hiroshi and Tomozo, involve her maintaining domestic harmony, often requiring her to raise her voice against their occasional misbehavior.

Her personality blends tenderness with practicality, though she easily flares at family antics. Her interests encompass embroidery, bowling, and ventriloquism. She admires singers Chiyoko Shimakura and Momoe Yamaguchi. Favorite foods include manju, yakisoba, tempura, and enoki mushrooms, while she dislikes natto and raw tomatoes. She treasures an opal wedding ring, acquired cheaply in youth but now considered valuable.

Her character remains consistent across all media portrayals, with no significant development or alterations documented in spin-offs or adaptations.