Shirahoshi

Shirahoshi, the Mermaid Princess (人魚姫) is a giant smelt-whiting mermaid and the youngest of King Neptune's children. She was first mentioned by Pappug, claiming he knew her and even promised to introduce her to the Straw Hat Pirates when they arrived at Fishman Island (though later this does not appear to be the case).

Appearance
Shirahoshi as a mermaid is described as "cute but huge" in her introduction. She is also described by many as one of the most beautiful woman in the world, rivaling that of Boa Hancock.

Personality
When she is first introduced she proclaims she is not afraid of a potential attacker (which she mistakes Luffy as) but despite her size, she is a cry baby. She seems to have a very fragile personality, quickly breaking out into crying fits when she first meets Luffy and also when Megalo disappears.

History
According to Pappug, Vander Decken IX started sending letters to Princess Shirahoshi once a week and soon, those letters grew into packages. When he started sending threatening marriage proposals, she became so terrified of him that she couldn't ignore him anymore. This angered King Neptune, and his sons gathered an army to find Vander Decken.

Her pet shark, Megalo, has been missing for some time having been swallowed by the Kraken. Shirahoshi kept crying and crying until the shark returned having been freed by Luffy after he defeated the Kraken.

When the Straw Hat Pirates were taken to the Ryugu Palace, Monkey D. Luffy wandered off on his own in pursuit of a smell of good food. Eventually, he stumbled upon her room, where Princess Shirahoshi was sleeping. It looked as though the room was attacked and seems like people were after her life. So it was built with the intention of keeping her safe from her attackers. Luffy was unknowingly walking across her stomach and fell between her breasts. When she woke up, she became greatly distressed. She thought that Luffy was one of the many attackers who have been targeting her life. She says she's not scared since she's the daughter of Neptune, but she starts crying to no end while asking for assistance.

Trivia

 * The largest species of smelt-whitings is the King George whiting growing to a length of 72 cm and 4.8 kg in weight. Overall the smelt-whitings are a relatively small fish averaging at 20cm in length and 100g in weight; in contrast to Shirahoshi's size, which is on par with giants.