Sakiko Sakura, the protagonist’s elder sister, enters the series at age twelve, born March 21, 1962. Her poised, disciplined nature positions her as the family’s steady anchor, though frequent clashes with her sister over borrowed items or social missteps reveal flashes of exasperation. She sports black hair tied in twin pigtails secured by pink bands, seven distinct bangs framing her face. Her outfits—a red-pink blouse, blue-green skirt, and yellow outdoor shoes—reflect a cheerful practicality. Unbound, her hair falls to her shoulders, reserved for sleep or rare occasions.

Diligence defines her: she thrives academically, earns a monthly ¥3000 allowance, and immerses herself in books on astrology, animal behavior, and handicrafts like knitting star-shaped charms or folding origami cranes. Her recorder melodies often drift through their home. Yet her sternness softens during crises, like shielding her sister from aggressive strays or sharing quiet, vulnerable moments that betray her deep-rooted protectiveness.

A fervent admirer of 1970s icon Hideki Saijo, she papered her bedroom walls with his posters and never misses his televised performances. Summer festivals showcase her goldfish-scooping prowess, a family trait enabling her to nab two fish in one swift motion.

Her dynamic with her sister orbits rivalry and devotion—sparring over trivialities yet fiercely defending one another. Their mother, Sumire, openly favors Sakiko’s academic drive, a contrast to her sister’s free-spiritedness. Though later narratives briefly amplify her irritability, her role as the family’s equilibrium persists. Sumire’s past as a youthful "Modern Girl" adds subtle depth to Sakiko’s inherited resolve, her consistency unwavering across adaptations, from live-action portrayals to spin-offs.