Yoko

Yoko is a little girl in Little East Blue who takes up her father's job as its protector. She is always seen wearing a Marine uniform, which belonged to her deceased father. She has a habit of biting people's heads who aggravate her.

History
Yoko was once the daughter of a Marine who decided to defend Little East Blue by himself. Five years ago, he died and left Yoko all alone. Saddened by his death, Yoko decided to wear his uniform and take up his mantle as the protector of Little East Blue.

Three years ago, she met Boss, a gigantic fire breathing beetle. Because of its strength which reminded her of father's, she became friends with the creature and they have been protecting Little East Blue since then.

As it was pirates that killed her father, she has a very raw hatred of them and is the only one who doesn't take kindly to the Straw Hats when they stumble upon the island, believing that all pirates are evil (Coincidentally, this is a similar viewpoint the Marines have).

However, after seeing how strongly the Straw Hats are protecting Boss and her Island, her views change towards them, even warmly saying goodbye to them as they left.

Trivia

 * Yoko has a similar appearance to Nami, like her she has also lost a parent, who was a marine, to pirates and shares Nami's old views on pirates before she became one herself.