Long before Mamoru found his destiny with Usagi, he gave a single rose in thanks to a lonely boy who helped him recover from the crash that claimed his parents. This long-forgotten friend, Fiore, has been searching the galaxy for a flower worthy of that sweet gesture long ago. This Xenian flower is beautiful, but has a dark side- it has the power to take over planets! To make matters worse, the strange plant is tied to an asteroid hurling towards Earth! Faced with an enemy blooming out of control, It’s up to Sailor Moon and the Sailor Guardians to band together, stop the impending destruction and save Mamoru!