Zenta and Matsuzo's boat arrives at the shore of an island populated by round-eyed Ainu people. Although they seem friendly, Zenta and Matsuzo soon learn that they are prisoners!

After fleeing to the Japanese settlement on another part of the island, Zenta and Matsuzo discover that the Japanese are making preparations for war. With conflicting views on the matter, Zenta and Matsuzo part ways. Can they prevent the battle or will they find themselves fighting one another?