Rubeus

Rubeus is one of Prince Diamond's commanders of the Negamoon Family, and the first to appear from the future to try and take over Crystal Tokyo. He travels inside a gigantic spaceship, where he makes his plans with his advisor, Wiseman, and his four servants, the Negamoon Sisters. His plans involved finding Rini and the Imperium Silver Crystal and taking over crystal points in Tokyo. All these plans failed, and soon the Negamoon Sisters were all turned good by Sailor Moon. Before this happened, Rubeus and the Negamoon Sisters faced off against the Sailor Scouts.

After the Negamoon Sisters turned good, Emerald appeared to rub it in Rubeus's face and tell him that Prince Diamond was going to kick him out of the Negamoon Family. Rubeus "evened the score" by capturing the other Sailor Scouts inside his ship, telling Sailor Moon to hand over Rini and the crystal. Sailor Moon and Rini entered his ship where Sailor Moon fought Rubeus, but he won a beam struggle against her Moon Scepter Elimination attack. However, he lost the next beam struggle when Rini broke his crystal that was his source of power, and he programmed his ship to selfdestruct in an attempt to kill the Sailor Scouts, however they teleported off the ship with Rini. Emerald appeared. Rubeus, having lost all his power, asked her to take him to the future, but instead told him that he "struck out" and teleported off the ship, which then exploded, killing Rubeus.

Rubeus can shoot dark energy waves and dark energy balls. His name is based off the gemstone ruby.