Sadi is the chief guard at Impel Down, with her name derived from the term sadism. Her appearance is reminiscent of a dominatrix, dressed in a revealing devil-themed outfit. She carries a pitchfork and wears a headpiece that looks like horns. Her long hair covers her eyes, and she adorns herself with candle-shaped earrings.
True to her name, Sadi is sadistic, taking pleasure in inflicting pain and torture on others, including Marine allies. She seems to revel in their screams. Sadi takes immense pride in the nearly flawless defenses of Impel Down and declines assistance from the Marines.
She often interjects "mmmmm--!?" into her sentences and insists on being called "Sadi-chan." As a chief guard, she holds authority over lower-ranking subordinates and appears to command the Four Demon Guards. The pitchfork she carries conceals a custom-designed whip, which she wields skillfully.
(Source: One Piece Wikia)
