The Amphisbaena III - S1.E11

The deserted island turns out to be a research facility owned by Magus Craft where Kanon's father, Kensei, conducts research. Kojou and Yukina are attacked by a vanguard force, but the one to save them from danger is Princess La Folia of Aldeigia, a young woman with deep connections to both Kanon and Kojou.