With the extermination of the human race about to begin, Princess Kahm and her Earthling fiancé Tetsuya arrive at the capital of the Santovasku Empire, a palace complex covering an entire planet! Although Tetsuya is already overwhelmed by the majesty and unimaginable technology of the Santovasku, he must now act as the sole emissary of humanity as he faces Kahm's father, the all-powerful Emperor of the Santovasku!