Sekai no hate no shima

After a dangerous journey, Esteban and his friends are washed up on a mysterious island. That night, a shadowy figure comes creeping towards them. Silently, the figure steals a chart and a pistol, then snatches up Zia. Esteban gives chase. He discovers a curious house in a tree, where Zia is a prisoner. To Esteban's surprise, the mysterious shadow turns out to be a friendly boy of his own age, called Tao.