Chapter 613

Chapter 613 is called "The Mermaid Princess in Hard-Shell Tower".

Cover
Short Term Cover Page: From the Decks of the World - Vol. 1: News Coo's travelling the world, bringing around newspaper telling everyone that the Straw Hat Pirates have returned.

Quick Summary
Shirahoshi screams and yells in need of help, being afraid Luffy will hurt her. Though, Luffy is her saviour, as she has become target of a big axe, thrown to her from far away. Vander Decken IX, has once again thrown a big weapon in her directions to try and kill her, for not marrying him. Meanwhile, Zoro is arrested and the remaining three (Brook, Nami and Usopp) take out guards, trying to arrest them too. As guards falter one by one, Neptune takes a swing at them, but is stopped by two swords of Zoro. Having broken out of the palace prison, he aids his friends. Back in Fishman District, Hody Jones and Vander Decken IX make a deal to take the head of Neptune.

Chapter Notes

 * Zoro is seen for the first time on Fishman Island.
 * Hordy Jones and Vander Decken IX make a pact that includes taking the head of Neptune, and overthrowing the Ryugu Kingdom.
 * Vander Decken IX is fully seen for the first time and his crew is called the Flying Pirates.
 * Vander Decken IX apparently ate a Devil Fruit, making him the first known fishman to do so. It appears that he was the one who threw the weapons at Shirahoshi's door.
 * Usopp introduces his new weapon, Black Kabuto.
 * This is the second time Luffy bluntly points out a person's negative qualities and says "I don't like you". The first time was with Coby.
 * Thanks to Luffy, Shirahoshi will apparently exit the tower for the first time in a decade.
 * On the newspaper announcing the Straw Hats' return on the cover, Sanji's picture shows only the back of his head, yet again continuing his bad luck in pictures as one of the Straw Hat Pirates.
 * Wadatsumi is revealed to be a fishman and not only a giant.