Shyarly

Madame Shirley (マダム・シャーリー) is a shortfin mako shark mermaid. She is a fortune teller living on Fishman Island and is also the proprietor of the Mermaid Cafe. Madame Shirley accurately predicted the dawning of the Great Age of Pirates, as well as the outcome of the Whitebeard War and Whitebeard's death.

Appearance
Madame Shirley is a very tall (or large) mermaid with manicured hands, sharp teeth and eyes that resemble shark eyes. She has short dark hair that is covered by a hood. She wears a blouse that is only buttoned in the middle, revealing her stomach and chest and has a string of beads around her waist. When angry, her eyes take on an ominous appearance. When introduced, she was seen smoking a pipe.

Personality
Madame Shirley is a very kind woman, as she lent the Straw Hat Pirates a room in which they could take care of Sanji. She also gave Keimi the rest of the day off so that she could spend time with her friends. She apparently doesn't like rudeness or vulgarity as she became very angry when Luffy asked if mermaids poop. However, her anger seems to be shortlived, as she calmed down and returned to her normal self almost instantly after Luffy apologized.

Even though she is a fortune teller, Madame Shirley regards her gift as a burden, since most of her visions are of bad things. As a consequence she thinks that the future is better left unknown. When she had a vision of a man in a straw hat who will be responsible for the destruction of Fishman Island, she went into a state of panic screaming that Luffy should be banished from Fishman Island.

Abilities and Powers
As a fortune teller, she has the ability to see into the future. She is also very accurate in her predictions as she predicted the Great Age of Pirates as well as Whitebeard's death. She was seen screaming in agony when a prediction came from nowhere about a man in a strawhat, who she presumes is Luffy, destroying Fishman Island. Also, as the proprietor of the Mermaid Cafe, she has complete control of the restaurant.

History
Some time prior to the current storyline, she made predictions about the coming of the Great Age of Pirates as well as Whitebeard's death.

Fishman Island Arc
She is first seen when the Straw Hat Pirates are in the back of the Mermaid Cafe, taking care of Sanji. She was the one who allowed them to use the back room. She asked Keimi about Sanji's recovery status. After Keimi's report, Keimi asked her not to go back and check on Sanji, as her beauty could be harmful to him, and to not let him know they are in the back of the Mermaid Cafe for the same reason. When Luffy and Usopp found her crystal ball, Shirley told them not to touch it. She went on to say that she had quit fortune telling, as the future was best left unknown. When Luffy asked if mermaids pooped, Shirley became furious at him, but was immediately quelled when Luffy apologized at the urging of Keimi. She then said that Keimi could take the rest of the day off, saying the cafe had enough staff so that it would not be a problem. After Keimi remembered she had to bring a clam to Pappug, Shirley told her that he was in the cafe, making quite a ruckus with an old friend of his. Later, she is seen shouting in the streets of Coral Hill about an impending doom. She had looked into the future after she felt something about Luffy. She goes on to say that Luffy must leave, as she saw a man in a straw hat destroying Fishman Island in her prediction. The three princes of the Neptune Family soon come to visit her. Having calmed down, Shirley tells Prince Fukaboshi about her prediction.

Trivia

 * As noted, the storyline of the Fishman Island arc draws many elements from "The Little Mermaid", Shirley can be considered a parallel with the sea witch in the storyline, whose magic had been responsible for the events within the storyline just as it is Shirley's prediction that is responsible for elements of the plot of the arc. In some cultures, fortune telling is seen as a part of witchcraft and black magic.
 * Madame Shirley's prophetic ability has also a predescent in Japanese folklore. The Amabie is a mermaid who could prophesize both good and bad fortune.