Nini, also known in the original Japanese version as Nene Sakurada, is a five-year-old girl and a classmate of Shinnosuke Nohara in the sunflower class at Futaba Kindergarten. She is one of the core members of the group of friends that often gathers at the Nohara household or plays together in the neighborhood. Nini lives with her parents, and her home life occasionally serves as a setting for episodes that explore the dynamics of her family, particularly her mother's sometimes volatile temperament.

Nini's most defining trait is her passionate love for a game she calls real omamagoto, or real house. Unlike typical children's make-believe, her version of house involves complex scenarios filled with divorces, arguments, and dramatic conflicts. She is the director and star of these plays, insisting on always taking the role of the mother and forcing her friends to participate, often through persuasion that borders on coercion. This reveals a personality that is at once creative and controlling. She enjoys crafting stories and scripts, demonstrating a vivid imagination and a desire to orchestrate events around her. Underneath her sweet appearance, she possesses a shrewd and somewhat self-centered streak, often manipulating situations to get her way and sometimes outsmarting both her peers and adults. This combination of innocent exterior and cunning interior is a recurring source of comedy in the series.

Her motivations typically center on asserting her will within her social circle, whether by directing her elaborate games, managing her friends, or expressing her often contradictory opinions. She is not driven by deep personal quests but rather by the immediate desires of a strong-willed child who wants to be in control and have fun on her own terms. Despite her bossy tendencies, she is a loyal friend to the other members of the sunflower class and genuinely enjoys their company, though she expresses this through her domineering style of play.

Within the story, Nini serves as a key member of Shin-chan's peer group, frequently challenging his antics or becoming exasperated by them. Her role often involves adding a layer of dramatic intensity to the group's adventures, whether through her imaginative games or her emotional reactions. She is a foil to the more laid-back personalities of some of the other boys, and her interactions with Shin-chan in particular are marked by a mix of irritation, competition, and underlying friendship.

Her most significant relationships are with her fellow classmates. She is often seen playing with Shin-chan, Masao Sato, Kazama, and Bo, though her interactions are frequently characterized by her attempts to boss them around. She has a notably complex dynamic with Shin-chan, as she finds his behavior both frustrating and amusing. Her relationship with her mother is another key aspect; her mother's own short temper and tendency to take out frustrations on her father mirror some of Nini's own bossy behavior, suggesting a familial influence. Over the course of the series, Nini's personality remains fairly consistent. While she matures slightly and learns from her experiences, her core traits of being theatrical, bossy, and creatively manipulative remain central to her character, providing a stable and reliable source of comedy and social dynamic within the group.

Nini's notable abilities lie not in physical prowess but in social manipulation and creative direction. She is adept at crafting elaborate role-playing scenarios and at convincing, or strong-arming, her friends to go along with her plans. Her emotional expressiveness, whether in joy, anger, or frustration, is another defining characteristic, allowing her to dominate any situation she is in.