Soya is an ordinary high school boy, aside from the fact that he lives with a large cat-like creature named Sensei and a happy green-haired maid named Ginko. One day at school, his city is under attack by a large UFO that appears to be an oddly-designed stuffed animal. All conventional weapons are useless against it, and it attacks by trapping the minds of anyone who gets close to it in a pleasant dreamlike state...