As Usagi Tsukino and her friends enjoy their ordinary high school lives, her boyfriend Mamoru Chiba prepares to study abroad in America. However, a tragic event unfolds at the airport when Mamoru vanishes mysteriously after proposing to Usagi. Distraught by his disappearance, Usagi represses the memory of that fateful moment. Soon, the menacing Shadow Galactica, led by the formidable Sailor Galaxia, descends upon Usagi along with the enigmatic Sailor Starlights. With the Sailor Guardians unsure of the Starlights' intentions, they find themselves stripped of their Sailor Crystals, the wellspring of their strength, by the all-powerful Sailor Galaxia. In a series of devastating encounters, the Sailor Guardians are mercilessly eliminated one by one. Left in a dire predicament, Usagi transforms into Eternal Sailor Moon to face Sailor Galaxia in a final, epic showdown.