Doronjo, whose real name is Hiroko Sasagawa, is the glamorous and cunning leader of the Doronbo Gang, serving as one of the primary antagonists. She is a tall, attractive woman with fair skin, blonde hair, and blue eyes. Her signature appearance features a revealing black and red outfit complemented by a mask that covers her eyes, marked with the letter D on the forehead. She is often seen smoking a distinctive skull-shaped pipe.

In personality, Doronjo is vain, smug, and intelligent, presenting herself as a formidable and fearsome villain. However, beneath this facade lies a degree of clumsiness and a tendency toward childish fits of rage when her plans are thwarted. While she is greedy and enjoys luxury, her deepest, often hinted-at desire is surprisingly mundane: to leave her life of crime and become a regular housewife. This internal conflict is a recurring theme, and in the 2008 series, she explicitly plans to use the wish-granting Dokuro Rings to achieve eternal youth and find a lover. She also harbors a subtle, mostly unrequited romantic interest in her archenemy, Gan Takada, also known as Yatterman 1.

Despite frequently yelling at and hitting her two henchmen, Boyacky and Tonzura, Doronjo genuinely cares for them. This loyalty becomes more pronounced over time; she is visibly distraught at the thought of losing them and feels regret after the gang temporarily disbands, showing that their bond is a true friendship. She also has a grudging respect for the Yatterman team, acknowledging them as worthy opponents.

Doronjo’s primary role in the story is as the leader of the Doronbo Gang, relentlessly pursuing the fragments of the Dokuro Stone or the Dokuro Rings on behalf of the mysterious skull-faced figure, Dokurobei. To fund their elaborate schemes and robot-building, the gang runs various fraudulent enterprises. A typical episode involves Dokurobei giving her a mission via an exploding device that often humiliates her, followed by the gang constructing a mecha to steal the treasure. They are invariably confronted by the Yatterman, and after a battle where their robot is destroyed, Doronjo and her gang escape only to be punished by Dokurobei for their failure.

Throughout the original series and its 2008 remake, this formula persists, but Doronjo shows notable development. In the original finale, after collecting all the Skull Stones only to discover they were the pieces of Dokurobei himself, who then departs leaving them with nothing, she tearfully disbands the gang and they go their separate ways. In the 2008 remake, a similar betrayal occurs, but after a temporary split, her longing for her comrades leads to a joyful reunion, and they choose to continue their adventures together. Later stories show that she eventually marries and becomes a mother of five, though she often reunites with Boyacky and Tonzura for further escapades, suggesting a deep nostalgia for her days as a thief. Her legacy continues in Yatterman Night, where her descendant, Leopard, takes up the mantle of Doronjo to lead a rebellion, and the original Doronjo is implied to be watching over her from the afterlife.

In terms of abilities, Doronjo is not primarily a physical fighter, preferring to direct her henchmen and command their mecha from the sidelines. Her true skills lie in her intelligence, smooth talking, and talent for orchestrating scams and deceptive schemes. She is a capable leader who plans the gang's operations. She also possesses the unusual, almost magical ability to blow smoke from her pipe into the shape of a skull. On the rare occasions she is forced to fight directly, such as in the Tatsunoko vs. Capcom game, she is shown to be capable but quickly exhausted, as it is not her preferred method of operation.