Himawari Nohara is the youngest child and only daughter of the Nohara family, born on September 27. Her first appearance was in a special episode depicting her birth. Her name, which means sunflower, was chosen by her older brother, Shinnosuke, through a drawing in the anime, though it was selected from viewer submissions in a public contest.

As an infant, Himawari is unable to speak, and her thoughts and intentions are instead conveyed to the audience through on-screen subtitles. Despite her baby status, she is depicted as a precocious, vibrant, and increasingly intelligent character. She has a mischievous and naughty nature, often causing trouble for her family. However, her infantile innocence means she rarely receives direct blame for the chaos she creates.

Himawari possesses several distinctive and strong-willed personality traits. She demonstrates a palpable lust for shiny objects, jewels, and brand-name goods, possessing a seemingly innate ability to discern a real gem from a fake one and discarding the latter. She also emulates her mother, Misae, in her stubborn pursuit of handsome young men. This particular interest can be used to pacify her, as her brother once discovered that she would calm down if presented with a cutout mask of a popular handsome actor.

In terms of abilities, Himawari is exceptionally active and physically capable for her age. She can crawl at an extremely high speed, a feat that can even tire out her energetic brother, Shin-chan. She is known to use the family dog, Shiro, as a toy and has shown surprising strength, such as being able to pull her mother when motivated. Her stubbornness and energy make her a handful for her parents.

Within the story, Himawari's primary role is as the family's beloved and troublesome baby. Her birth added a new dynamic to the Nohara household, creating new opportunities for comedy and chaos. She shares a significant bond with her brother, Shinnosuke. Despite their sibling rivalry and her occasional annoyance with him, she clearly looks up to him, often imitating his actions and mischievous habits. For his part, Shin-chan is often tasked with looking after her, and he is protective of her despite their quarrels. Her father Hiroshi and mother Misae are deeply affectionate towards her, though her antics often add to Misae's daily stress.

Her relationships extend beyond her immediate family. Toru Kazama, one of Shin-chan's friends, thinks of Himawari as a little sister and has fantasies of marrying her when she grows up, a future that is hinted at in some official media. Another friend, Masao Sato, also sees her as a sister figure and dreams of her calling him onii-chan. Among her peers, Himawari has been known to engage in rivalry, such as with Nene Sakurada over the attention of a handsome authority figure.

While Himawari remains an infant throughout most of the series, her character has shown development, maturing and growing more intelligent over time. Glimpses of her future have been provided in various films and specials. In the movie Super-Dimension! The Storm Called My Bride, an adult Himawari appears, working as a police officer and later as a secret agent. In this future portrayal, she retains her characteristic sideways glance and blush when encountering a handsome man. Another film, Fierceness That Invites Storm! Me and the Space Princess, centers on her being identified as the prophesied princess of the planet Himawari, leading to her temporary abduction. Special manga chapters have also depicted her as a five-year-old, where she is shown to be just as chaotic and troublesome as her older brother.