Unlimited Fafnir

Yuu defeats Kili in a fight to decide Tear's fate. As part of the agreement, Yuu's plan to destroy Basilisk goes forward and Yuu orders Kili to live on as a human. Kili kisses Yuu as she leaves asking him to show his superiority by defeating Basilisk. Mitsuki devises a strategy to defeat Basilisk with all possible fallback scenarios planned out. The students drop with the Mistileteinn and protect it from the first catastrophe beam discharge by Basilisk's third eye, but with the discharge having come much sooner than anticipated that the third eye had time to fire the catastrophe beam a second time, which destroys Mistileteinn. However, the blast creates an opening for the students to disable the third eye and immobilize Basilisk, allowing Yuu to destroy Basilisk using Babel. The students return to Midgar as Mitsuki's outlook on life has changed to a more optimistic one and Yuu tells Iris about his memory loss as a condition for using Babel, and Iris vows to stay with him.

After the Dylan's plan has gone awry, the execution of a new operation is entrusted to the Midgar. Having analyzed Basilisk's third eye, Haruka gives an overview of the new strategy to the students of class Brunhild, which is to form pairs and launch a strike on Basilisk, by infiltrating the volcanic island. She orders them to carry out the attack before the catastrophe beam can be fired. For this operation, the pairs consist of Yuu and Iris, Mitsuki and Ariella, Lisa and Ren, and Firill and Honoka. Yuu uses the dragon ability "anti-gravity", and he has a flashback to the time he was told by Charlotte that Mitsuki also has something akin to his power.

With Basilisk headed towards Midgar, Class Brynhildr heads to an uninhabited island to draw Basilisk away from Midgar knowing that it is after Tear. On the way to the island, Mitsuki and Lisa are at odds with each other over Miyako's death. Mitsuki explains her relationship with Miyako to Yuu. She was very close friends with Miyako, but she became a dragon when the Kraken invaded Midgar. Miyako ordered Mitsuki to kill her and Mitsuki reluctantly complied. With Yuu's help, Mitsuki and Lisa make amends with each other.

Kili attacks Midgar with the dragon Hecatoncheir that can regenerate. While Lisa looks after Tear, she is attacked and overpowered by Kili. Wanting to protect her friends, Tear agrees to go with Kili and become the Basilisk's wife. But Yuu convinces Tear not to go with her while he awakens the power of Leviathan to defeat Kili.

Tear enrolls at Midgar Academy and claims Yuu as his wife as he was the person who saved her life when a fire burned down her home.

Loki tells Yuu that it is his duty to prevent the girls at Midgar from becoming dragons and to kill them if they do. Iris has been having suicidal thoughts as she is dangerously close to becoming a dragon, but Yuu convinces her to think about living. The girls prepare for combat as Leviathan approaches the island.