To close the Keystone Gate and seal the portal to Nod, the Japanese government calls for the destruction of Itogami Island, dispatching Yukina and Natsuki to the bottommost layer of the structure. But when the time comes for her to pull the trigger, Yukina wavers between following her orders and saving the island she loves. In the midst of this predicament Kojou-having regained his vampiric powers-shows up to oppose her. The story of the world’s mightiest vampire and his Watcher finally draws to a close!