Usagi befriends new student Ami Mizuno, a genius girl who gets perfect grades. The two go to Game Center Crown, where they win two pens from the Sailor V arcade game machine. After Ami goes to Crystal Seminar, Usagi and Luna look into a disk Ami received and realise that it is a hypnotising program tricking people into finding information on the Silver Crystal.
Usagi uses the pen she received from the arcade to disguise herself as a doctor. She sneaks into the Crystal Seminar to rescue Ami who is in a trance, but is overpowered by the Youma. Ami snaps out of her trance, and uses the pen she received to transform into the Sailor Senshi known as Sailor Mercury.