The Straw Hats visits an island, known as Mecha Island, where a fisherman sings an old folk song about a Golden Crown. Searching for that mysterious treasure, they find a hidden entrance into the island. The island's leader, Ratchet, impressed with the find and in search of the Golden Crown himself, invites the crew to join him in his search and the crew along with Ratchet and his henchmen enter the cave. As it turns out, the islands true form, is that of a giant turtle. Ratchet, who had known this all along, uses his mechanical castle to take control of the turtle, in order to use it, to take over the world. Now the Straw Hats have to stop not only Ratchet, but also the helpless turtle, from crashing into a nearby island.

There are three kinds of swindler. One, called the "WHITE SWINDLER", finds a mark and steals money. The "RED SWINDLER" preys on the other sex and steals a mark's body and soul. Then there is the "BLACK SWINDLER". Ignoring ordinary marks, targeting only the white and red swindlers, and preying on their flesh grown fat and corrupt with the money they have stolen, he is the worst of them all. There is a boy who once became a victim of a swindler and lost his family. Later, he turns into the most hideous "black swindler" to deceive only other swindlers. His name is Kurosaki. This time, he is requested by Reiko, whose daughter is sick, to hunt down a swindler named Ishigaki, who has defrauded her of money. But, behind Ishigaki, there is actually a bigger swindle which has even destabilized the Japanese economy…

After getting married and having a daughter, a retired legendary hitman must protect his family when his past catches up to him.