A giant army of monsters suddenly attacks Fort Tilia. Among all the chaos and death, Takahiro and Lily must decide whether to reveal their secret, and invite suspicions that they were behind the entire attack. But if they don't act, their new friends in the fortress will be in danger!

Meanwhile, the cheaters of the exploration team, Juumonji Tatsuya and Watanabe Yoshiki, prepare a counteroffensive plan to repel the invaders alongside the army. However, at the final hour, the unimaginable happens. None can peel their eyes from this development!