The demon legion descends upon the city to claim the God Key while the humans go on the defense. A happy Amira appears before Favaro, claiming she met her father within the city, before dashing off. The King's forces battle the demons at a losing pace while Amira happily stuffs herself inside the kitchen while Favaro, Kaisar and Rita attempt to get information about her father. Azazel infiltrates the castle, leaving carnage behind as he seeks Amira who is now passed out. He proceeds to taunt Kaisar about his father's death, admitting his involvement but Favaro takes the blame and challenges Azazel, buying time to get Amira and the God Key away. Eventually Kaisar comes back to aid Favaro and Azazel recalls he is actually the killer of both their fathers. Kaisar sacrifices himself to buy time for Jeanne to charge up her sacred weapon Maltet who then delivers a decisive blow to the distracted Azazel. The tide changes, the humans winning and Favaro manages to save Kaisar but in the meantime when Rita finishes fighting and goes back to wake Amira she finds her missing.

With Favaro transformed into a demon, he is now under their control. Beezlebub and Martient prepare Amira for transportation but not before blasting Kaisar away to fall into the depths below. The god clan attempt to maintain the seal on Bahamut but sense the presence of the Transcendent Key now that it is formed. Meanwhile Azazel converses with Rita and Bacchus, revealing that Beezlebub is the one behind Amira's actions as well Martinet; Rita theorizes Martient is not a demon like Beezlebub. While protecting the seal the angels are attacked by the corrupted Jeanne who slays Raphael and Uriel before going after Michael. Kaisar is saved by Bacchus in his flying carriage only to be attacked by Jeanne. While Bacchus fights Jeanne, Rita gives Kaisar a cure she made for the demon transformation and he taunts Azazel into helping him. Rita attempts to administer the last of the antidotes to Jeanne but fails only for Michael to successfully give it to Jeanne through a kiss after she impales him. Jeanne is freed, turning back into a saint while Michael's physical form disappears and he reassures her the world needs her. As Beezlebub prepares to destroy the angels protecting Bahamut's barrier Azazel attacks him and engages in battle for revenge. Kaisar duels with the demonic Favaro and upon seeing how he's become a true demon shoots him in the chest. Amira emerges from the Transcendent Key's orb, now with angel's wings. Lavalley appears before Kaisar, only for Rita to warn to get way from the knight. With the barrier fallen Bahamut beings to absorb Amira while everyone looks on helplessly; as Kaisar watches in disbelief Lavalley shoves him over the edge of the flying fortress before reveling in Bahamut's awakening.

War erupts between humans and gods. To get the upper hand against the fast-advancing gods, Charioce XVII activates a weapon that was slumbering deep underground. Just when Nina and the others are escaping from the dungeon, they're thrown into the heat of battle.