Sailor Moon and the Sailor Guardians unite to save Earth from an alien force! When he was still a child, Mamoru gave a single rose as thanks to an alien boy who helped him cope with the loss of his parents. Since then, his long-forgotten friend Fiore has searched across the galaxy for a flower worthy of his gesture. Fiore’s final choice is the beautiful Xenian flower, which has a very dark side - it has the power to fatally drain energy from human life! Now, Sailor Moon and the Sailor Guardians must go into space to stop the impending destruction and save Mamoru!