Underground. The Aomori Twin Bridge was cut off, and enough food wasn't reaching Aomori where Sakura and the others lived. Meanwhile, a phantom beast appears on the twin bridge again. However, the 4th Squadron is removed from the Twin Bridge battle and is in danger of being disbanded. In order to remove the stigma of the "useless unit", Sakura and the 4th company will challenge the newly appeared small phantom beasts...