Bishoujo Senshi Sailor Moon is based heavily on Greek Mythology. Tuskino Usagi is actually a recarnation of the moon goddess Selene, and Chiba Mamoru, Endymion. Their tale comes from the tale of Selene and Endymion. Here is the story:
Endymion was the handsome son of Zeuse and the Nymth Calyce, an Aeolian race though Carian by origin , and ousted Clymenus from the kingdom of Elis. His wife, known by many different names, such as Iphianassa, Hyperippe, Chromia, and Neis, bore him four sons; eh also fathered fifty daughters on Selene, who had fallen desperately in love with him. Endymion was lying asleep in a cave on Carian Mount Latmus one still night when Selene first saw him, lay down by his side, and gently kissed his closed eyes. Afterwards, some say, he retured to the same cave and fell into a dreamless sleep. THis sleep, from which he has never yet awakened, came upon him either at his own request, because he hated the approach of old age; or because Zeus suspected him of an intrigue with Hera; or because Selene found that she preferred gently kissing him to being the object of his too fertile passion. In any case, he has never grown a day older, and preserves the bloom of youth on his cheeks. But other's say that he lies buried at Olympia, where his four sons ran a race for the vacant throne which Epeius won. -from THE GREEK MYTHS:1 by Robert Graves
Other myths claim:
Endymion, the shepard,
as his flock he guarded,
She, the Moon, Selene,
Saw him, loved him, sought him,
Coming down from heaven
To the glade on Latmus,
Kissed him, lay beside him.
Blessed is his fortune.
Evermore he slumbers,
Tossing not nor turning,
Endymion the shepard.
-from Greek Mythologyby Edith Hamilton
Nevertheless, it is because of his surpassing beauty that untimely caused his singular fate: endless beauty, rest, and youth.
More about Selene:
Selene, the moon goddess, is the daughter of Titan Hyperion and the Titaness Theia (or her mother was Euryphaessa, according to others.) She is sister to Helios, Eos, and Titan. However, she is most known for her countless love affairs, including Endymion along with Pan and Zeus.
