Domino serves as the Head Jailer, also referred to as the Chief Guard, of the great underwater prison Impel Down, holding her position under Warden Hannyabal following the events of the timeskip. She is a slim woman with long, wavy blonde hair, typically styled with a tuft covering her right eye while her left eye is obscured by a pair of sunglasses. Her uniform is a modified version of the prison's standard militaristic attire, consisting of a short, pale brown double-breasted jacket worn like a dress over a white shirt with a black tie, paired with brown boots and notably long gloves. She completes her look with the standard Impel Down hat.

In terms of personality, Domino is depicted as a very strict and serious individual who demonstrates a no-nonsense dedication to her duties. This trait is most famously illustrated when she scolded the former Warden, Magellan, for spending an excessive amount of time in the washroom, warning him that such tardiness would tarnish their professional record. However, despite her professional demeanor, she is not immune to distraction, as she, like many others, was momentarily enchanted by the extraordinary beauty of the Pirate Empress, Boa Hancock.

Domino's primary role within the story occurs during the Impel Down Arc, where she acts as an official escort and security officer for the prison. She is first seen greeting Boa Hancock and Vice Admiral Momonga upon their arrival at the prison, before Hancock is set to be taken to see the imprisoned Ace. Tasked with conducting a full-body search on the Warlord, Domino leads Hancock to a private room and requests she remove her mantle for inspection. Unbeknownst to Domino, Monkey D. Luffy was hiding underneath Hancock's large robe. Before she could discover him, Hancock used her Mero Mero no Mi powers to petrify Domino, allowing Luffy to escape into the prison. After being restored to normal, Domino appeared confused and had no memory of failing to properly complete the search, and she subsequently accompanied Hancock to meet with Chief Magellan on Level Four.

Her key relationships within the prison hierarchy are primarily professional. She answers directly to the Warden, either Magellan before the timeskip or Hannyabal afterward, and her role as a high-ranking officer places her in command of lower-level employees. Her interactions are largely defined by her adherence to protocol, such as when she coordinated with Hannyabal to explain the prison's brutal baptism procedures for new inmates and ensured that Hancock followed the rules, including the use of Seastone handcuffs.

Regarding her development, Domino holds the rank of Head Jailer after the two-year timeskip, a promotion from her earlier position. This advancement came after the previous head jailer, Shiryu, betrayed the prison to join the Blackbeard Pirates. In her appearances after the timeskip, her appearance has slightly changed, as she no longer wears a white shirt under her jacket and is sometimes depicted with a white coat over her uniform.

In terms of notable abilities, Domino's authority as a high-ranking jailer gives her command over the prison's staff and operations. She has been seen carrying a whip as a weapon, although her level of proficiency with it remains unknown. Her primary function is as an enforcer of the prison's strict rules and procedures, and her character serves as an obstacle for Luffy's infiltration mission, though she is ultimately neutralized by Hancock's Devil Fruit power.