Long ago, Japan was home to several navies. The Murakami Navy, said to be the strongest of them all, once defeated even Nobunaga, and refused to join Hideyoshi, choosing to pursue their love of freedom and the sea. The man who led these samurai of the sea was the great pirate lord Takeyoshi Murakami. And now Kaede Murakami, a descendant of Takeyoshi, is an elementary schooler living on an island. On her 12th birthday, Kaede discovers a flute in her family's storehouse that has been passed down through the Murakami family for generations. The flute holds the key to finding the Murakami Navy's buried treasure. This adventure story tells the tale of an ancient pirate and his descendant forming a connection that transcends time, uniting the island.