Domino is the Prison Chief of Impel Down who serves under Hannyabal.
Appearance
OmDomino when kids.
Domino is one of the top officers at Impel Down, and looks the most professional. She is a slim blond woman with long wavy hair, with some hair always seen covering her right eye, while the left one is covered with sunglasses. He wore a modified military uniform, consisting of a light brown short jacket that was worn like a dress over a white shirt with a black tie, all matching brown shoes and black gloves that were longer than the other officers. On his head, he wears a standard Impel Down hat.
Two years later, he did not wear a white shirt under the jacket again but was bare-chested, even though his cleavage was covered by a tie. His hair is also shorter, and it seems he is wearing a robe. He is depicted playing football.
Personality
Domino, a very strict and mysterious person, was seen as he scolded Magellan for spending too much time in the restroom. Even so, he, like most people, melted on Hancock's beauty, and did not remember that he did not carry out a thorough body examination of Hancock.
Ability and Strength
He was seen carrying a whip but it was unknown how well he used it.
History
Impel Down Arc
Domino first appeared to do an examination on Boa Hancock's body, which made him petrified with the power of Mero Mero no Mi, so Luffy (who hid behind Hancock's big robe) was undetected. After that, Domino turned back to normal (and was also a little confused, being unable to remember what happened to him while checking his body) and accompanied Boa Hancock to Head Magellan's office on Level Four.
About three hours before Portgas D. Acedieks execution, Domino appeared outside Magellan's restroom to inform him of the preparations for Ace's transfer to Marineford. He scolded Magellan for spending a lot of time in the restroom, and said that it would contaminate their records if it was too late. He was last seen holding Den Den Mushi to Magellan during the runaway second wave prisoner.
Two years later
During the timeskip, Domino was promoted to Head of Prison Impel Down after the incumbent had previously resigned and joined the Blackbeard Pirates.
Source : WIKIA ONE PIECE