Detective Conan: Jolly Roger in the Deep Azure

1700 times, Anne Bonny and Mary Read are 2 female pirates which protected their country from being attacked from england. People who sail to sea all fear JOLLY ROGER which was formed by red flag Jolly Rouge & devil OLD ROGER. Now 2007. Conan won in a gazette riddle and Mori used the money on vacation inside Koumi island with the kids and Ran. Iwagana, Koumi travel guide, wish to avail tourists' wisdoms to find Anne Bonny's 1700 plotted treasures. What was the precious treasure that Anne Bonny kept inside Yoriyajima since 1700 times when she worked with Mary Read?