Captain Gorou Edajima and Petty Officer Hajime Tokushima take a submarine through the gate and into the Blue Sea, sent to recover an American journalist held somewhere in the Special Region. Reaching her means reading a coastline nobody has charted, where local rulers and pirate fleets are already fighting over the shipping lanes. Takumi Yanai moved the story off land for this novel sequence, which follows the original Gate books instead of retelling them.