Tetsu is a young warrior who has left his home country in order to serve human rulers in their battle against the dark elves. But one day the valiant knight was heavily wounded in battle. Unconscious, he was found by a female fighter named Mei, who brought him to her house and cured him. Grateful, Tetsu promises Mei to help her venture into the huge tower standing nearby, which was built by the princess of the country and is now overrun by monsters...