Hatabō is a recurring character from the Osomatsu-kun franchise who appears in the Mr. Osomatsu anime as an adult. His most defining physical feature is a miniature Japanese flag that is perpetually planted in the top of his head, an unusual characteristic he has carried since childhood when his skull was pierced by it. He is notably short in stature and maintains a childlike appearance, including a single protruding bucktooth and a shaggy bowl-cut hairstyle. His typical outfit consists of green overalls worn over a light-colored top, an ensemble that reinforces his youthful, almost toddler-like presentation despite being the same age as the Matsuno sextuplets.

In terms of personality, Hatabō comes across as simple-minded, innocent, and remarkably naive. He does not seem to fully grasp the complexities of adult life and instead drifts through his existence with a vague, unburdened sense of purpose. His speech is often punctuated by a verbal tic, frequently ending sentences with a drawn-out "da jo" or similar sound. Despite his quiet and unassuming demeanor, there is an underlying strangeness to him that becomes apparent in certain situations. He possesses an unsettling capacity for retaining information, which he terms "selling information," and his actions can sometimes carry a darker, more severe implication than his innocent face would suggest. He retains many childish habits, such as riding a child's tricycle and a persistent longing for friendship, indicating that he has not emotionally matured alongside his physical age.

Hatabō's role in the story of Mr. Osomatsu is that of a supporting character and a childhood acquaintance of the Matsuno brothers. His most prominent storyline occurs when the sextuplets are invited to his birthday party, expecting to find an even greater failure than themselves. Instead, they discover that Hatabō has become staggeringly wealthy and powerful, having built a massive information-brokering empire under the alias Mr. Flag. In this capacity, he commands a legion of identically flag-headed employees and deals with powerful figures, showcasing that his financial success far outstrips that of the main cast. However, this fortune and status prove to be fleeting. He loses his entire empire when his employees stage a revolt, recognizing that his success was built on luck rather than competence and that he lacks any real business acumen. Following this downfall, his role reverts to that of a more isolated and innocent figure.

His key relationships are primarily defined by their inconsistency. He is an old acquaintance of the Matsuno sextuplets, who view him with a mix of condescension, pity, and later, jealousy. For his part, Hatabō treats the brothers as friends, showing them generosity by offering them vast sums of money from his vault. His relationship with other recurring characters like Chibita and Iyami is fluid, varying depending on the needs of the skit. He may be portrayed as a follower or buddy to Chibita, or sometimes as a rival or even outright enemy. With Iyami, he is often vulnerable, with Iyami targeting him for scams or petty crimes as part of a group of children. In some older interpretations, the character Dekapan is occasionally presented as his father or a mentor figure.

Hatabō is a character who resists static development, often fluctuating between different states. His most significant arc sees him rise from a forgotten, simple man to the ultra-wealthy Mr. Flag, only to lose everything and return to a state of innocence and social isolation. This financial collapse seems to soften or diminish the more unsettling and severe aspects of his personality, with his default later portrayal being that of a kind but simple-minded man. Despite these dramatic swings in fortune, his core essence remains largely unchanged: he is a being of childlike innocence and naivete, seemingly adrift in a world he does not fully comprehend.

Regarding notable abilities, Hatabō's primary skill is his unexpected success in information brokerage, which allowed him to amass a fortune despite his apparent incompetence. This success appears to be less a product of cunning and more a result of persistent luck. He also demonstrates a bizarre resilience, as the flag remains embedded in his skull without any apparent ill effect. On occasions, particularly during his wealthiest period, he wields immense financial power and can command the loyalty of a small army of employees. There are also allusions to a more menacing capability, as he once sold a "mystery meat" from mobile vendors following an employee dispute, the exact nature of which remains disturbingly ambiguous.