When a massive, unearthly monster appears out of nowhere on the skyline of a Japanese city, the expected happens: the Japan Self-Defense Forces roll out the tanks while the public panics. Nobody knows what it is or where it came from, but Yuki, a brave and inquisitive adolescent, has a secret that could be a useful clue. Tetsu, her friend, has been secretly caring for a strange creature called Cenco, which will soon reveal some remarkable, even impossible, characteristics. Another adolescent boy, a stranger with some mysterious connection to the monstrosity attacking the city, appears, and his unwelcome interest in Tetsu's pet snuffs out any doubt of a connection—and lights the fuse for the upcoming battle.