One of many guardian dragons of the archipelago, Lee never seems to have anything to do. When a pirate ship makes it past the outer islands to chase down a young witch, he leaps at the chance to prove himself. The witch, Amili, explains that the pirates are after the precious treasure hidden somewhere among the islands. The two of them agree that they should try to find it before the pirates do, which means enlisting the help of Lee's grouchy ex-girlfriend, whose only obsession is someday travelling through the stars. Their adventure will take them to depths they had never imagined.