Luna becomes suspicious of the new girl in school, Ami Mizuno. Usagi also joins in on the suspicion when they find a brain-washing program on a disk that Ami leaves behind as she rushes to cram school. Usagi enters the school by disguising herself as... (more) a doctor with the Luna Pen. After transforming into Sailor Moon, Usagi realizes the cram school teacher is the monster, not Ami. The monster tries to steal Ami's energy, but a symbol appears on her forehead...