Yukina moves into the room next to Kojou's. When Kojou sees that she only has a bare minimum of furniture and necessities, he takes her to a hardware store. Kojou's younger sister Nagisa also insists on hosting a welcome party for Yukina, adding up to a very lively day.

The morning after the battle against the Combat Deacon and his homunculus, the town is left in ruins. Yukina had been shocked to see how vastly Kojou's power exceeded that of the Familiar, but now she learns that Kojou can't even control his own Familiars. Kojou and Yukina pursue the escaped Eustach and Astarte to an abandoned laboratory, where another intense battle awaits them...

Eustach and Astarte continue their assault, finally launching an attack on the central support of the manmade island. When Kojou learns that Asagi is trapped inside, he's eager to save her, but his inability to control his own Familiars holds him in place. Unable to see him go on like this, Yukina makes a suggestion he never expected...