Sadi

Sadi-chan is the chief guard of Impel Down. Her name comes from the word sadism. Due to the "-chan" part of her name coincides with the Japanese honorific, people tend to mistake it as such.

Appearance
Sadi-chan resembles a dominatrix in design. She dresses in a very skimpy red (in anime hot pink) devil-themed outfit. She carries around a pitchfork and wears a headpiece that resembles horns. She has long orange hair that covers her eyes and wears candle-shaped earrings.

Personality
As her name suggests, Sadi-chan is a sadistic person who enjoys bringing pain and torture to others, including Marine allies, and can't seem to get enough of their screams, getting sexually excited hearing them. She also seems to have extreme pride in the virtually perfect defenses of Impel Down, and refuses the assistance of the Marines.

She also tends to add an "mmmmm--!?" in the middle of her sentences, and insists to be addressed as "Sadi-chan", which is to correct people in case they think the "-chan" is an honorific (which is not, but is part of her name).

Abilities and Powers
Sadi-chan is a chief guard of Impel Down with some authority over lower ranking subordinates. Being in command over the Four Demon Guards, she is considered "stronger than four of them combined", much that they cower in fear whenever the sadist gets angry. The pitchfork she carries around conceals a custom-designed whip which she can use quite adeptly. She is also fairly strong in her own right, taking out a section of the bridge over the Pool of Blood during Luffy's and Iva's mass breakout.

Attacks

 * Kōfun no Geki: Akamamuchi (興奮の檄・赤魔鞭, Arousal Manifesto: Red Demon Whip): Sadi-chan whips at her opponents with her pitchfork. This attack is strong enough to smash the stone bridge in Impel Down's Level Four.

Impel Down Arc
Sadi-chan was first seen standing outside the gates of Impel Down, refusing the assistance of the Marines in capturing Luffy, and ordered them to fortify Impel Down's outer defense. When Impel Down's forces were gathered in Level 4, she was shocked after hearing the Minotaurus' defeat. She was later assigned to guard the entrance to Level 5, where Magellan deduced Luffy will head, with the assistance of three Demon Guards. She was then seen serving sake to them while waiting.

After Luffy's capture, she went to Level 3 and ordered the Demon Guards, as well as her other subordinates, to hunt for Mr. 2 Bon Kurei, who slipped to Level 5 with them unaware. Sadi-chan became very angry over the Demon Guards' failure to locate Mr. 2 Bon Kurei anywhere on Level 3, violently whipping them as a punishment.

After Luffy, Ivankov, Inazuma, Jinbei and Crocodile escaped from Level 6, she was ordered by Hannyabal to go down to level 4 to confront them herself. She is seen with the other guards showing shock after Luffy, Jinbei and Crocodile effortlessly defeated three of the Demon Guards. Angered over this she goes on the attack herself, using her whip to knock out a huge amount of prisoners, taking out a chunk of the bridge over the Pool of Blood in the process, highlighting her massive strength in battle. Luffy nearly attacks her, but Iva throws him over the Chief Guard and battles Sadi-chan herself. Despite her efforts, she was later revealed to have lost the fight, and among other injuries has had her back broken. Having been tied up with her own whip hanging from the ceiling, Magellan ordered his subordinates to untie her.

Marineford Arc
Although the Blackbeard Pirates broke out of Impel Down as well, it is unknown what hapened to Sadi-chan and the rest of Impel Down staff.

Major Battles

 * Sadi-chan vs. Impel Down Prisoners
 * Sadi-chan vs. Emporio Ivankov

Translation and Dub Issues
Like Boa Hancock, Sadi-chan has also received edits to her clothing so that the bottom of her chest is no longer visible in Viz's Shonen Jump. Her top instead fully covers her chest and the frills are removed. This edit will likely be present in the actual volumes of the manga.

Trivia

 * She is the second character to have a Japanese honorific problem with the word "Chan" in the name, the first being Hatchan who caused fan confusion over whether or not his name was an honorific.