Makoto comes to the conclusion that the Black Moon are actually after Chibi-Usa, as opposed to the immeasurably powerful Silver Crystal. The three remaining Sailor Senshi are determined to safeguard Chibi-Usa, as they are sure that she may hold the key to all of their questions and mysteries. Meanwhile, Petz is causing a deadly disease to spread all over the city that infects Makoto and causes her to become ill.