Galactic Teacher CAO-2 Strikes Back! Urusei Yatsura : Season 5 Episode 8

Oyuki meets with Lum, Benten, and Ran to warn them that their old elementary school teacher, CAO-2, has escaped. CAO-2 was a huge, menacing robot teacher shaped like a huge chalkboard eraser. He ran his class with an iron fist, had zero-tolerance for all the pranks that Lum and Benten pulled on him, and often punished them by hurling himself at them. The girls managed to trap him on a stalactite on some remote planet after a chase through space, but now that he's escaped, he's looking for revenge!