1x12 - 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.