Hina, known by her epithet Black Cage, is an officer in the Marine Corps who holds the rank of Rear Admiral. She is a tall and slim woman with a striking appearance, characterized by straight, waist-length pink hair parted in the middle and dark eyes. Hina typically wears a purple two-piece suit, a white Marine jacket draped over her shoulders like a cape, and dark gloves. She is often seen smoking a cigarette and has a particular verbal tic, frequently referring to herself in the third person, such as saying "Hina is disappointed" or "Hina failed." Despite the cute nature of this habit, she does not attempt to act cutely and generally presents a stoic and professional demeanor.

Hina is a highly rational and pragmatic individual. She is dutiful and follows orders, but she is not blindly obedient, demonstrating a clear understanding of the World Government's political machinations. For instance, she advised her colleague Smoker to accept credit for defeating a Warlord of the Sea to avoid being court-martialed, acknowledging that the government intended to cover up the true events. When faced with failure, she is respectful and level-headed, having calmly admitted defeat after a failed attempt to capture Monkey D. Luffy. Her professionalism stands in contrast to the rebellious nature of her long-time friend, Smoker, whom she has often helped protect from the consequences of his insubordination.

Hina joined the Marines alongside Smoker, and while she was a model cadet, he was a troublemaker whom she frequently had to bail out. This history forged a strong, lasting friendship between them, and they continue to interact with a familiar ease, with Hina addressing him as Smoker-kun. She also has a unique relationship with her subordinates, Jango and Fullbody. The two men are her ardent admirers and tend to follow her around, often dancing and goofing off. Hina finds their antics annoying and does not reciprocate their romantic interest, but she tolerates them and took them into her unit in recognition of their combat abilities.

Within the story, Hina serves as a supporting antagonist and a capable Marine officer. She was first formally introduced during the Alabasta incident, where she attempted to capture the Straw Hat Pirates as they were leaving the kingdom. Her pursuit was thwarted by the shape-shifting powers of Mr. 2 Bon Kurei, who tricked her by disguising himself as Luffy. Later, while vacationing on Kyuka Island, she took the opportunity to capture remaining members of the Baroque Works organization. During the Summit War of Marineford, she was summoned to reinforce the Marines and engaged Luffy in battle, though he managed to evade her powers. In the story's current timeline, she has been shown escorting the Nefertari family of Alabasta to the Levely and is present at Marine headquarters during significant global events.

Hina is a formidable fighter and a skilled unarmed combatant, able to defeat powerful hand-to-hand fighters like Mr. 2 Bon Kurei. Her primary strength comes from the Ori Ori no Mi, a Paramecia-type Devil Fruit that gave her the nickname Black Cage. This ability allows her to create iron restraints from any part of her body. When she swipes a limb through a target, that body part turns into an iron bar that binds them. She can also extend her arms to form a large, prison-like cage to trap multiple opponents. In addition to her personal abilities, Hina commands the Black Cage Corps, a specialized Marine unit that includes a squadron known as the Black Spear Squadron. She has also demonstrated keen perceptiveness, being able to see through disguises by cross-referencing them with wanted posters.