Hachisuka Goemon serves as a ninja under Yoshiharu Sagara, having previously pledged allegiance to Kinoshita Toukichirou before his death. She transferred her loyalty and a shared promise to rise in the world to Yoshiharu upon Toukichirou's demise, actively supporting his missions and safeguarding his life. Goemon leads the Kawanami group, a band of thieves once commanded by her father; she assumed leadership following his passing.

Physically petite with a youthful demeanor, Goemon is often mistaken for a child due to her stature. She possesses short silver hair, bright pink eyes, and a round face. Her standard outfit includes a black, sleeveless kimono-style top, black arm-warmers, leggings, forearm and shin armor, tabi socks with waragi sandals, and a black scarf she occasionally uses to conceal her face. Turquoise headwear adorned with pink skulls completes her look. She carries multiple weapons, notably a ninjatō and throwing knives. Goemon frequently emphasizes the importance of wearing a loincloth beneath her clothes, declaring it essential "ninja's spirit."

Confident, enthusiastic, and a capable leader, Goemon stays calm under pressure but enjoys dramatic explanations. Her speech is marked by an inability to deliver long sentences without stuttering or pausing, a trait that worsens when embarrassed or pressured, especially if Yoshiharu hugs her or calls her cute. Highly proactive, she undertakes dangerous tasks like infiltrating enemy camps without hesitation. While remarkably composed in life-threatening situations—such as taking a bullet for Yoshiharu—she reacts strongly to physical affection or perceived impropriety, a reaction linked to her recent awareness of men.

A recurring trait is her tendency to propose lethal solutions to problems, whether concerning enemies or even crying children, often as dark humor. For example, she once suggested letting Hanbei Takenaka's uncle die to manipulate her for the Oda clan's benefit, though she later admitted this was a test of Yoshiharu's morals. Initially pragmatic and encouraging Yoshiharu to accept sacrifices for greater goals, she gradually warmed to his idealistic methods and aligned with his approach.

Her background remains largely undisclosed beyond her father's role and death. Her relationship with Yoshiharu is central; she protects him from the shadows and collaborates closely. The Kawanami group idolizes her for her cuteness and stuttering, maintaining fierce loyalty. She also shares good terms with Inuchiyo Maeda due to their mutual duty to protect Yoshiharu.

As a ninja, Goemon excels in stealth, combat, and reconnaissance. She melts into forests or urban environments, often undetectable except to Yoshiharu. Proficient with weapons like smoke bombs and blades, she incapacitates foes non-lethally and undetected. She is highly skilled at gathering intelligence and leading the Kawanami group. While dismissing supernatural ninja myths like flight, she demonstrates technical prowess through feats such as vaporizing large volumes of water. Her name fuses the historical figures Hachisuka Masakatsu and Ishikawa Goemon, reflecting her dual heritage as both retainer and rogue.