Kazuhiko Hanawa, most often called Hanawa-kun by his classmates, is a third-grade elementary student and a recurring figure in the series. He stands out immediately for his unmistakable appearance, which includes neatly brushed, side-swept brown hair, a stark contrast to the simpler hairstyles of his peers. His wardrobe is notably more formal and extravagant; his standard school attire consists of a cream shirt with a white collar, an indigo waistcoat, an orange-red tie, black shorts, and polished black shoes. In the summer, he switches to a crisp sailor-style uniform, complete with a blue neckerchief and matching shorts. This careful attention to his clothing is one of the first indicators of his privileged background.

Hanawa is a kind and gentle boy, though his speech and mannerisms carry a distinct, posh air that comes from being raised in a very wealthy family. He often adopts an elegant speaking style and has a habit of addressing his female, and sometimes male, classmates as baby, a quirk that underscores his sophisticated self-image. He generally avoids negative topics, preferring to find the positive aspects of any conversation. However, his behavior can occasionally tilt towards the snobbish, particularly when his own possessions or lifestyle set him apart from his less affluent friends, often without any malicious intent but simply as a reflection of his reality. He is deeply concerned with his reputation and can display genuine shock or dismay when a situation tarnishes his perfect image, such as being told his handwriting is illegible or experiencing an embarrassing public mishap. Despite his wealth, he is not unkind; he is genuinely generous, often sharing his good fortune by bringing back souvenirs from his overseas trips, hosting holiday parties at his mansion, and freely inviting his friends over to play or satisfy their curiosity about his luxurious home.

His motivations are largely driven by a desire to maintain his refined image and to be helpful to those around him. He seems to genuinely enjoy being the center of attention, a position his wealth and experiences naturally grant him. Underneath this, however, there is a consistent motivation to act in a manner that is impressive and commendable. This is frequently seen in his interactions with the protagonist, Maruko. On several occasions, Hanawa shows a particular interest in being seen positively by her. Examples of this include his embarrassment when he forgets to bring a container for a captured frog, fearing he looks incompetent, and his willingness to lend Maruko his own four-wheel bicycle to help her learn how to ride. He also fulfills many of her quiet wishes, from hiring a professional photographer for her family portrait to hosting a private cherry blossom viewing party just so she can see the flowers.

Within the classroom, Hanawa plays a key role as the wealthy, internationally-minded student whose life is a source of fascination for his peers. He often serves as a catalyst for special events or adventures. For instance, his connections led to a group of foreign exchange students, including a boy from Italy, staying with the local families, an event that became a major story point. His keen interest in pets and animals also leads him to share duties as a class pet caretaker alongside Maruko.

His most significant relationships are with his classmates. He is a friend to many, though his bond with Maruko is particularly notable and receives frequent focus. While Maruko initially found him strange and affected, Hanawa repeatedly demonstrates a deep, quiet care for her that goes beyond mere friendship. He teases her affectionately, compliments her appearance, and makes promises to her that he keeps, such as gifting her a bouquet of nine roses for her ninth birthday with a pledge to add a new rose each year. This behavior has led many viewers to interpret his actions as a childhood crush, making their dynamic one of the more endearing and closely watched interactions in the series. Other classmates include the studious and serious Maruo, as well as Migiwa, who is known to have a crush on Hanawa, a feeling he does not reciprocate.

Hanawa’s background is defined by immense wealth and privilege. His parents are almost always traveling abroad for business, leaving him in the care of his mother and a life of material comfort but also a degree of independence. This upbringing has provided him with a broad range of talents and hobbies not accessible to most nine-year-olds. He takes weekly lessons in English, French, piano, violin, and even Indian philosophy. His English is notably fluent, to the point where he can easily give directions to a lost foreign visitor. His abilities also extend to more practical matters; he is a skilled tennis player and enjoys playing cards. Perhaps his only notable shortcoming is his poor handwriting, which is often cited as being nearly illegible, a small flaw that makes his otherwise perfect character more relatable and human.