Nagi has disappeared on the mainland. Karasuba is so worried and anxious that she is unable to do any work. Worried about her, the Black Cat dolls come up with a plan: for Haizakura and Karasuba to leave the imperial capital and go to the mainland in search of Nagi. With passports in hand, the great search begins in the land of perpetual winter... Haizakura: "Come on, look for something important!"