Following Makoto's capture, Luna and Mamoru discover one of Petz's Malefic Black Crystal earrings and have Artemis analyze it. Frustrated by her failure, Minako proposes to Usagi and Mamoru that they talk with Chibi-Usa, who appears to have made a friend named Momo, only to see her freak out upon seeing the earring. Meanwhile, as the other members of Black Moon become curious about their advisor, Wiseman, Rubeus sends the final Spectre Sister, Calaveras, who uses her medium powers to call upon the powers of her fallen sisters. As Usagi remains upset that Chibi-Usa refuses to tell her anything, her friends show her a DVD of Calaveras allegedly channeling Rubeus, setting up a public channeling session to lure out Minako. The next day, Usagi discovers Chibi-Usa has taken her transformation brooch while Minako comes across Calaveras as she uses her powers to possess others with the spirits of her sisters. Just as Usagi and Chibi-Usa are confronted by Rubeus, they are saved by Mamoru, who awakens his own power to stop Rubeus' attack and prevent Minako from being captured. After Usagi comes to Minako's aid and defeats Calaveras, Chibi-Usa explains that she comes from the 30th century to seek Sailor Moon's help in saving her time.