Nico Robin The Mysterious Woman

Not much is known about Nico Robin. Her mother, Olivia Robin, was an archeologist and was killed by the Cipher Pol 9 (a top-secret crack navy unit). At age 8, Nico Robin started to study the forbidden Poneglyphs--forbidden because some Poneglyph tablets contain clues to weapons of such terrifying power that it was deemed prudent to have their secrets locked away. She is one of the few people in the world capable of reading Poneglyphs. It was also around this time that it was learned that she had eaten a Cursed Fruit: the Hana Hana Fruit. This gave her the ability to sprout arms and hands out of practically anywhere, be it on a wall or on a person.

Nico's giant of a friend, Jaguar D. Saul, protected her from a fleet of ships that were closing in by throwing them against one another. After the whole incident, the World Government placed the 79,000,000 beri bounty on her head (a bounty probably topped only by those of the Seven Warlords of the Sea), because she escaped from the besieged island, and since she's a Archaeologist studying Poneglyphs, they blamed her for the destruction of the ships and gave her the enormous bounty to make the public more observant of her and turn her in.

In the present day, Robin has considerable skill with her Cursed Fruit power. Some of her nastiest attacks involve sprouting limbs on the enemy's body and then proceeding to contort said enemy in ways best left to the imagination.

When Crocodile formed Baroque Works, he hired Robin as his #1 assistant (thus the alias Miss Sunday/Miss All-Sunday). He needed her knowledge of the Poneglyphs in order to find one of the forbidden weapons--a fabled ship known as Pluton. While working for Baroque Works, she helps Luffy and the Straw Hat crew to escape from Baroque Works when they were being chased, but her intentions are unknown. Eventually, however, she cooperates with Crocodile and helps to capture Vivi, Luffy, and the Straw Hat Pirates. However, Crocodile loses patience with Robin when their search for the forbidden Pluton in Alabasta turns up a blank, and he turns on her.

After Luffy manages to defeat Crocodile, she decides to join Luffy's Straw Hat Pirates as crew archeologist. However, after all she had done as part of Baroque Works, this took more than a little convincing. Naive Luffy was eager to let her join, and a few hints of hidden treasure bribed Nami. Zolo would prove to be the real hardcase, but he ultimately relents, and Nico Robin becomes the 7th member of the Straw Hat Pirates. Besides archeology, Robin also studies the related field of history. This is why she has her suspicion of the connection between Luffy and Gold Roger--Luffy's D middle initial.