Tomozou Sakura, the 76-year-old grandfather of Momoko "Maruko" and Sakiko Sakura, resides with their family in 1970s suburban Japan. Born October 3, 1898, his bald head, tanned complexion, and signature grey-blue shirts paired with dark green pants—swapped for short sleeves in summer—anchor his recognizable presence. Blending warmth with eccentricity, he peppers family conversations with childhood anecdotes, sometimes veering into awkwardness. His emotional transparency surfaces through abrupt mood shifts, like deflating when Maruko spurns his company or rallying to shield her from parental scoldings.

Maruko often exploits his soft spot, coaxing snacks, meals, or cash—even nearly persuading him to fund a bus-ride escapade. A nostalgist at heart, he crafts spontaneous "Haiku of the Heart" verses, channels focus into Go matches, and showcases unexpected talents like goldfish scooping and ventriloquism. Though harmoniously partnered with wife Kotake and maintaining a typical dynamic with son Hiroshi, his deepest bond lies with Maruko, whom he comforts during emotional lows.

Notable details include a ¥80,000 monthly pension, a cherished Indian hat, and a cryptic "red paper" military summons hint from episode 43. Culinary preferences favor boiled tofu, natto, and sea urchin, while persimmons earn his disdain. Contrasting the author’s strict real-life grandfather, his whimsical traits underscore the series’ focus on generational connections and domestic warmth, his character remaining steadfastly consistent throughout the narrative.