Opting to stay hidden inside a box within the ship, Kaina, Ririha and Yaona find themselves offloaded to the mobile fortress of Valghia. Now, they must somehow come up with a way to return to Atland, but Valghians are hot on their tails.

Just before the start of the war between Atland and Valghia, Kaina and his friends race to get proof of a great tree that can save everyone, including their enemies.