Luna senses a strange aura around Usagi's genius classmate, Ami Mizuno, and thinks she might be a Dark Kingdom spy. Ami Mizuno is a very intelligent, reserved girl who is often seen alone at school. With the conviction that she help her to be more intelligent, Usagi befriends the girl and invites her to the game center. Ami leaves a floppy disk in the game center, Luna and Usagi realize it's an artifact from the Dark Kingdom and mistake her for an enemy. But she understands later that Ami Mizuno is Sailor Mercury, a Sailor Guardian as Sailor Moon, and their duties are the same. (Source: Wikipedia)

Aired on: 5/1/1992