Rubius was in charge of trying to find Chibiusa, aka Small Lady and get the Ginzuishou (Silver Crystal) from her. If he succeeded, Crystal Tokyo could be stopped. For the most part of his reign, Rubius didn't do much. He just spent most of his time in his spaceship and sent one of the Ayakashi Sisters down to earth to do his bidding. After he realized that the Sisters couldn't really accomplish much except bicker, he went down himself. Rubius met his end rather flashily. He had gotten the senshi into his spaceship and had set it to blow up. The senshi made it out, Rubius didn't.
