Shirahoshi - しらほし

First Appearance: Chapter 612 A giant smelt-whiting mermaid and the youngest of King Neptune's children. She was first mentioned by Pappug, who claimed he knew her and even promised to introduce her to the Straw Hat Pirates when they arrived at Fishman Island (though later this is revealed to be a lie). ~!She is the Ancient Weapon Poseidon.!~ (Source: One Piece Wikia)