Despite their initial intentions not to alter history, they soon find themselves gradually drawn into the war, though they continue to refuse to choose one side over another. The struggle of the crew from a modern, peaceful, and wealthy Japan to resist the nationalistic appeal of defending their country, knowing that in this time it is ruled by a brutal, totalitarian and militaristic government is the central theme of "Zipang." Their rescue of an Imperial Japanese Navy officer from the past, Lt. Commander Kusaka, who would have perished in the normal timeline, causes unstoppable and devastating changes in the past when he seeks to create a stronger Japan no matter what the cost.