Jun-Jun is a member of the Amazoness Quartet, a group of four girls who serve as antagonists in the Dead Moon Circus arc. She is easily identified as the tomboy of the group, possessing an athletic build, tan skin, and long light green hair that is styled into three distinct ponytails, one pointing upward and two angled downward. Her standard attire as a circus performer consists of a green two-piece loincloth bikini paired with pale mint green, Arabian-style pants, reflecting the magical circus aesthetic. As the acrobat of the Quartet, her specialty is tightrope walking, and she is referred to as the Magician of Acrobatic Feats.

In terms of personality, Jun-Jun is impulsive, hot-headed, and easily frustrated when things do not go her way on the first attempt. She speaks with a hard edge, using very informal, masculine speech patterns, and creator Naoko Takeuchi has described her as vulgar and a Yankee. Despite her tough exterior, she possesses a hidden sense of honor and humanity. Unlike her sisters, she often displays a degree of patience, allowing her targets to briefly enjoy their dreams before she moves to take their Dream Mirrors, a trait that echoes the nurturing aspect of the Roman goddess Juno. In quieter moments away from her mission, she enjoys relaxing with video games, sauna baths, and massages, adhering to the belief that one must look good to feel good.

Jun-Juns primary motivation throughout the SuperS storyline is to serve the Dead Moon Circus under the leadership of Zirconia and Queen Nehelenia, with the specific goal of locating the Golden Mirror that contains Pegasus. She hunts victims by using her green Amazon Stone to create nightmares that extract a persons Dream Mirror. A unique trait among the Quartet is that Jun-Jun exclusively summons male Lemures, the monsters sent to attack targets, many of which have fish-themed appearances. Her combat style is distinctly sporty and aggressive; she attacks by hitting explosive energy orbs or bombs toward her enemies using a baseball bat. She possesses several named techniques utilizing her orb, including Colliding Ball to extract Dream Mirrors, Rolling Ball for direct offense, and Through Ball to pass through solid objects.

Jun-Juns role in the story evolves significantly from a straightforward villain to a redeemed ally. She operates closely with her sisters CereCere, PallaPalla, and VesVes, though she easily becomes angry when they take command of a mission. As the conflict with the Sailor Guardians progresses, she and her sisters begin to question their allegiance to the Dead Moon Circus. After they assist in capturing Sailor Chibi Moon, they are betrayed and imprisoned in mirrors by Zirconia. In a pivotal moment of redemption, Jun-Jun rebels against Nehelenias control by shattering her Amazon Stone, thereby giving up the eternal youth that bound her to the villains service and helping to turn the tide of battle. Her true background reveals that she is not originally a minion of the Dead Moon Circus. She was originally one of four Sailor Guardians destined to protect Sailor Chibi Moon in the future, known as Sailor Juno, guardian of the asteroid Juno. She and her sisters were corrupted and awakened prematurely from their slumber in the Amazon Jungle by the nightmare energy of Queen Nehelenia. Following Nehelenias defeat, the corruption is lifted, and Jun-Jun reverts to her true form as a Sailor Guardian before returning to her long sleep, awaiting the day she will properly awaken to fulfill her duty to the future Crystal Tokyo.