The sealing ceremony for the relic of The Cleansing is finally underway. But just as it seemed the problem was taken care of once and for all, the ceremony gets interrupted by an incredible surge of magical energy coming from below. Avrora, the disaster sleeping at the bottom of Kannawa Lake, has awoken... In an attempt to rescue Nagisa, Kojou and Yukina venture out onto the frozen lake and find themselves facing off against a mysterious flying dragon; a vicious encounter that sends them sinking beneath the frigid waters. They awake in a hot springs inn to find that their wounds have healed completely thanks to an equally-mysterious girl named Glenda. But just who is she? And can she be trusted...?